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[Illustration: He caught the gunwale and pulled himself up and into the
boat with Curt's aid. (Page 21)]




                                  THE
                             MYSTERY CRASH


                             By VAN POWELL

                        [Illustration: Airplane]

                    THE SAALFIELD PUBLISHING COMPANY
                        Akron, Ohio    New York

                           Copyright MCMXXXII
                    THE SAALFIELD PUBLISHING COMPANY
                 _Made in the United States of America_




                                CONTENTS


  I The Deserted Airplane                                              5
  II At Rocky Lake                                                    12
  III A Greater Mystery                                               19
  IV The Sky Squad is Formed                                          28
  V A Double Puzzle                                                   36
  VI Suspicion and Suspense                                           42
  VII In the Falling 'Plane                                           53
  VIII Watchful Waiting                                               59
  IX Strange Actions                                                  67
  X A Summons                                                         76
  XI A Trail and a Flight                                             81
  XII The Chase                                                       93
  XIII The Detective's Theory                                         98
  XIV The Sky Squad Disobeys                                         104
  XV A Triple Trail                                                  112
  XVI The "Windsock"                                                 121
  XVII "The Case Is 'Sewed Up'"                                      128
  XVIII A New Mystery                                                136
  XIX Tangled Threads                                                144
  XX A Package of Money                                              151
  XXI Caught and Cleared!                                            159
  XXII The "Mystery Crate"                                           171
  XXIII Bob Pursues!                                                 179
  XXIV Suspense!                                                     188
  XXV Crossed Wires                                                  197
  XXVI The Sky Squad Goes Into Action                                207
  XXVII Driven Down                                                  219
  XXVIII Curt's Discovery                                            227
  XXIX A Confession                                                  235
  XXX Barney Gives a Hint                                            246
  XXXI "One More Problem"                                            257
  XXXII Flight!                                                      268
  XXXIII The Sky Squad Wins                                          277




                           THE MYSTERY CRASH




                               CHAPTER I
                         THE DESERTED AIRPLANE


"See that! Look! There's our mystery!"

Bob Wright pointed from the cabin window of the monoplane. Al, his
younger brother, peered toward the ground.

"What? Where? Show me any mystery!"

To make himself understood above the roar of the engine, Bob put his
lips close to Al's ear while Curt, Bob's closest friend, also a
passenger, bent close to catch his words.

"It's a mystery all right--but you can't see from here. It was in that
cornfield we passed over."

"What's the mystery?" Curtis Brown's eyes snapped with eagerness.

"Why did you say 'our' mystery?" Al asked at the same instant. Bob
answered both at once.

"The mystery is: Why is an airplane hidden in the grove at the edge of a
cornfield? Our mystery because we discovered it and because, ever since
we helped father solve his detective cases and took an interest in
aviation we have wanted to solve something that connects up puzzles and
'planes!"

"A 'crate'?" Al stared out. "I don't see it." Bob was not there to
reply. He moved up to the pilot, Langley Wright, his cousin, who was
test pilot for the Tredway Aircraft Corporation and who was giving this
beautiful "job" its final test and check flight.

"Lang," he said, "I saw an airplane in the grove at the edge of that
last field we crossed. Circle back, won't you?" As Lang turned from
jotting down some data, Bob added: "The ship hasn't crashed. It's in
among the trees--backed in. I caught a glimpse of it, and then the trees
hid it. I'd like to have another look."

"Surest thing you know."

Lang, twenty-one and an expert flyer, grinned at his sixteen-year-old
cousin, dipped ailerons, kicked rudder and with a good "bank" as the
craft swung its nose around, he deftly counteracted a tendency of the
ship to go into a sideslip, jotted down some information on his data
board and then looked out of his window.

"There's the field," he said. "I don't see a crate there!"

"That's why I told Al and Curt it's a mystery," Bob replied. "The ship
has been hidden! Its tail is in between trees, and the wings are under
trees with high branches. I don't believe it could be seen from the
highway that runs by the field. I know it wouldn't be noticed from the
air, except by chance."

"Hm-m-m!" grunted Langley, "I've heard of hidden treasure, but this is
the first hidden 'plane----"

"There!" Bob pointed past Lang's face.

"I see it!" Lang continued to circle, in order to get another sight of
the mysteriously hidden ship. As they came around again Al and Curt
located it also.

"It's staked down!" Al, although he was the youngest, not much past
thirteen, had the quickest eyes of the group. "I saw the stakes, and
rope over the wing-tips."

"The engine was covered over," added Curt.

Lang spiraled down to pass as close as the trees would allow.

They saw nothing more, however, and after Lang had refused Al's
impulsive request to "set down" in the small field, the party flew on to
the landing field of the Aircraft Corporation where Lang had some
alterations to report in the adjustment of the ship's balance before it
could be delivered to its purchaser.

"Let's get our bicycles and ride out to the field," urged Al, as the
trio of comrades alighted beyond the aircraft plant.

They pedaled the three miles in record time.

"I was right," commented Bob, as they left the wheels beside the highway
and climbed over the high rail fence enclosing the stubble where corn
had recently been cut down. "You can't see the airplane from any place
along the highway----"

"Unless it's gone," interrupted Al.

"No!" Curt was a little ahead. He waved his arm. "There she is!"

They crossed the rough field, toward the mysterious, silent object of
interest.

"I can see from here it hasn't cracked up," Curt declared. "Not a
scratch on it and the landing gear is perfect."

"Whoever flew it must be clever," declared Bob. "Look at the narrow
strip of open, smooth ground he had to 'set down' on. If he hadn't been
able to shoot the field so as to get in on that long, smooth side, with
only a few feet clearance, he'd have come down in rough stubble."

"Yes, he must have been good," agreed Al. "And it proves that he was
forced down. Any sane pilot would have gone on to a better spot."

They reached the airplane, a two-winged model with a radial motor and
small wings; it was a speed ship, trim and mystifying with its dark,
brown body and airfoils freshly done.

Curtis, whose age was midway between Al's thirteen and Bob's sixteen,
clambered onto a landing wheel and observed the instruments on the dash.
"Plenty of gas, and oil," he remarked. Then his companions saw his face
change.

"Look!" As he called he leaped from his perch so that Bob could occupy
it; Al was up on the other side, and it took no explaining to show what
had caused Curt's exclamation. Both youths saw the small square of paper
pinned to the folded parachute on the seat.

"Dare we look?" questioned Bob.

"'I can read it from here," Al said, and reported. "It says, 'Everything
O.K.'"

"Crickety Christmas!" Curt resorted to his favorite expression.
"'Everything O.K.' Then it wasn't a forced landing."

"No," agreed Bob. "It didn't seem like one, somehow. The ship is too
carefully tucked away. And, now--this note. Who is it to? Who put it
there? Does it mean the ship is all right--or something else? I was
right when I said--'there's our mystery.'"

"You were!" admitted Curt.

"But what can we do about it?" objected Al. "Take turns watching? Wait
to see who comes back, and what he does?"

"I think not," counseled Curt. "It may be a mystery why the crate is
here, and all that! But it isn't any of our business--is it?"

"No," admitted Bob. "Let's go home, and see what father thinks of it.
There is probably some easy explanation we haven't thought of."

"All right. We can ride out here first thing--early--tomorrow."

They could not consult the private detective whose success had been so
pronounced that cases came to him from distant cities: he was out of
town that night.

When they rode out to the field the next day, at sunrise, looking for
the mysteriously deserted airplane it was gone!

"Where is your mystery now?" Curt was inclined to poke a little fun at
Bob. "As the sleight-of-hand performers say, 'Now you see it, now you
don't!'"

"Anyway," Al who was poking about in the grass under the trees, bent and
then exhibited a damp, crumpled paper, "here is the note. Now, what do
you say if we have a session of the old Master Sleuths, and see what we
can deduce from this paper?"

A year before, asked to do a little investigating for Mr. Wright, when
he was handling a case where youths would be least likely to arouse
suspicion by shadowing, the trio had become intensely interested in
detective work and had termed themselves the Master Sleuths, more in fun
than in earnest. However, when they had become "air minded" the term had
been dropped. Al, reviving it, won a grin from Bob.

"All right," Bob agreed. "The paper is damp. It has been out in the dew.
Under the trees it would take a good while for it to get as soggy as it
is. The writing has smudged--it's sort of purple----"

"It was written with an indelible pencil," remarked Curt.

"Then all we have to do is to find a man with an--" Al was not allowed
to finish. Bob broke in, as older brothers like to do.

"Yes--get 'the man in the gray suit!' How many indelible pencils do you
suppose there are in this country?"

"All right!" Al took the matter good-humoredly. "Anyhow, if a man wrote
it and a man read it and threw it away--two hands have handled it." He
put it carefully in his pocket. "There may be fingerprints."

"What good will they do?" asked Curt. "The mystery is all done with."

"No it isn't!" cried Bob, holding up his hand.

"Listen!"

From above came the drone of an airplane engine.




                               CHAPTER II
                             AT ROCKY LAKE


"I hear it!" exclaimed Al. He ran out onto the turf that had been used
as a runway, probably, when the airplane took off.

"So do I," agreed Curt, following him. "But I don't locate it."

Bob, craning his neck, staring up toward the great banks of clouds which
the early sun was painting with rosy fire, looked puzzled.

"Come to think of it," he said, "we ought not to hear it at all."

"Why not?" demanded Curt.

"He ought to be too far away."

"How do you make that out?" Al was incredulous.

"Easy! Lang came home a little before daybreak. He had been at the
airplane plant all night, with the 'mechs' because Mr. Tredway wanted to
get that Silver Flash ready for delivery in a rush. I didn't go to sleep
again. I got up, and dressed and went out to tighten the handlebar on my
bicycle. I glanced up, just as day broke, at the little windsock I have
on our roof."

"The wind was directly _West_."

"I don't see--" began Al; but Curt, wetting the back of his hand, tested
the air in various directions.

"You use your head, Bob," he said admiringly. "The breeze is pretty
strong, and it has shifted around _to South_, straight from the
Equator."

"Are you two trying to be mysterious?" Al was a little bit annoyed.

"I thought you wanted to be a Master Sleuth, last year," remarked Curt.
"Use your eyes and your brains."

"Um-m-m--the airplane must be gone a long time because the wind was West
and now it's South--um-m-m. Oh!"

"'Ah-ha!' cried Shawkhaw," Bob mocked, twisting the famous Hawkshaw
title as he made fun of his brother.

"This turf runs East and West." Al ignored Bob's mockery. "That biplane
was a speed model and it would have to get up higher speed than the
average to take off. The runway is too short to give it a good run, so
it couldn't very well have hopped off in time to get over the trees
unless it took full advantage of the wind! Isn't that it, Bob?"

"That's it. The wind changed about the time we left our meeting point
with Curt. So that airplane ought to be well on its way, wherever its
way leads."

"But this engine is getting louder," stated Curt.

"There it is!" cried Al, pointing toward the South. "It's only a speck.
But you see it, don't you, Curt?"

"Yes."

"So do I," added Bob.

"It looks as if it is spiraling down--yes, it is!"

"And it isn't the biplane we saw here, at all," Bob said. "Curt, do you
know what?----"

"Yes. It's the very 'plane we were in yesterday, with Lang. He gave it a
final check-up and said if they worked on it all night it would be ready
to take off today. That's it, all righty! The biplane was brown,
and----"

"This is the Silver Flash! I can see it glisten against that dark
cloud," added Al. "I think it's coming down."

"It's diving."

"No!" cried Bob. "It's out of control! It's falling!"

"Right over Rocky Lake!" shouted Curt.

"Come on!" urged Al, scrambling over the short stubble in the field, in
haste to reach his bicycle and pedal toward the picnic grounds, less
than a quarter of a mile away, in which Rocky Lake was situated.

"Wait!" counseled Bob.

"No! Come on!" Curt agreed with Al. The airplane was out of control. It
was diving, straight toward the amusement ground around the lake. "It's
a crack-up!"

"There it goes!"

Behind the trees, out of sight, like a silver streak, a comet, the
airplane fell. Three hearts went cold as the ship was lost to view
behind the foliage. While they could not see the craft strike, any spot
in Rocky Lake Park was bad for a landing: dense trees, whole groves,
alternated with stands, pavilions, and the deep, boulder-studded water
of Rocky Lake and the rivulet which fed it.

Three minds worked as one, three pairs of legs tumbled their owners over
the stile, onto the roadside turf, up to the bicycles.

Pedaling like madmen they made short time of the trip to the edge of the
amusement spot.

"I think it was directly over Rocky Lake!" Curt, in the lead, called
over his shoulder.

Dropping their wheels by the roadside they ran, winded but determined,
towards the picnic grounds.

"There--there--in the lake!" gasped Bob.

"It crashed, all right!" panted Curt.

"It's half buried in the water." Al puffed along a little to the rear.
"I hope the pilot----"

"It wasn't Lang, was it?"

"No!" Bob responded to Curt's question. "It must have been some other
pilot--I can't think who, though."

"Hurry!" urged Al. "Hello--hello!" he called, passing the pavilions. "Is
anybody around! Wake up--somebody! Help! Help! A 'plane has cracked up
in Rocky Lake!"

"See anything of the pilot?" Bob turned to Curt. Gasping for breath they
had reached the shore of the lake, by a small wharf where rowboats were
hired during the day.

Curt scanned the surface of the lake.

Quite near the shore, and on the rocks, with one crumpled wing, and with
her nose and cabin buried in soft, oozey mud, the smashed monoplane lay
with its pitifully useless tail assembly sticking up into the air. The
"flippers" had carried way with the impact and hung by the control
cables.

Bob turned a serious face toward his companion.

"I hope--I wonder"-- He could not finish. The thought flitted through
his mind that unless the pilot had been extremely quick and very clever,
he could not have gotten out of the cabin--in time. The falling craft
had been close enough so that had any figure leaped, especially with a
parachute, they should have seen it clearly.

No such figure had leaped--in time.

"Maybe he--crawled out when it struck," said Curt, hopefully.

"Anyhow, let's get a boat, and try to get to it."

"Al," called Curt, "stop calling for help! There isn't anybody here. Run
to the farmhouse across the road--no, that's empty. Ride back down the
road, till you see an automobile and send it to town for help. If you
don't meet one, stop at the first house and telephone."

Al, for all his natural eagerness to be at the scene, to share in their
experiences, saluted without a word of remonstrance and hurried away.
Meanwhile Bob, realizing that the oars for the boats were locked in the
small pavilion on the wharf, determined to break in, feeling that the
emergency removed any taint of robbery or pillage from the act.

Fortunately he found the old, rusted lock not caught. He slipped the
rusty padlock, slipped the hasp free, and ran back to the dock where
Curt had a boat untied and ready. In this, pushing off, they rowed out
to the airplane. The weight of its engine was very slowly driving its
nose deeper into the soft ooze of the marshy ground at that end of the
lake.

"Hurry!" begged Curt, as Bob bent to his task.

Suddenly Bob rested on his oars.

"What's the matter?" cried Curt, and as he saw the expression of Bob's
face he, too, became intent.

"There it is again!" panted Bob. "A call--a call for help?" he
questioned.

"I don't know. But row!"

Bob rowed.




                              CHAPTER III
                           A GREATER MYSTERY


"There comes the call again!" whispered Curt. "It was 'help!'"

Bob sent the boat through the mirrorlike water. He headed for the
immersed nose of the airplane and as they rounded the cabin, part of it
sticking up forlornly, Curt lifted a hand to point.

"Look! There is the parachute, partly inflated, floating on the water."

"It looks as though the pilot tried to get out of the cabin, and either
pulled his ripcord too soon, or else some part of the harness caught and
held him--until too late!"

Sobered and worried, wondering just what to do and who had called, they
sent their eyes questing here and there--into as much of the cabin as
they could see from the window just under the transparent surface of
Rocky Lake, but without result.

"I thought he might be caught in the cabin," said Bob. "But I can't see
any----"

"There he is--see! Out on the lake!" Curt pointed. "He's swimming."

Bob pushed away from the fuselage of the sinking craft, and with a sweep
brought the bow of their boat around.

"Oh!" he caught sight of a head bobbing in the water, "oh, Curt--I'm so
glad!"

Rowing hard, he sent the boat toward the swimmer.

"So am I." Curt's voice was relieved. "The pilot escaped."

"But--it can't be the pilot, Curt."

"Why not?"

"He has been swimming toward the 'plane, from out in the lake."

"I know, Bob, but he may have seen us."

"But he'd have part of the parachute harness on," Bob objected.

"Probably he slashed it off. Maybe he saw it was too late to get out,
that the 'chute was too low, and he slashed himself free and started to
swim across the water----"

"No. He'd have come to this closer shore, and landed on the wharf."

They watched the man, treading water as he saw them coming.

Across the water a call floated clearly to them.

"Did you hear--a call--for help?"

"We thought we did," Bob called back, and, as they came closer the man
spoke less loudly.

"I don't see anybody."

"Then you aren't the pilot?"

"He can't be!" Curt commented when the man failed to reply, being busy
clearing water from his eyes to look around the lake again.

"Haven't seen anybody at all," the man spoke as he caught the gunwale
and pulled himself up and into the boat with Curt's aid. "Heard a shout,
though. Row back boys, to that thing."

They went back over the course. The stranger, studying the aircraft,
seemed very much disturbed and worried. He had a hand ready to catch the
struts of a wing as they swung under the tilted airfoil: while Bob
stowed the needless oar on that side he drew the boat forward.

"We didn't see anything in the cabin. We looked, before," Bob explained.

"Untie that painter," the stranger ordered. "I'm going down under the
nose, and the mud might hold me--so, if I signal, you pull." As Curt
unknotted the tying rope and threw it to him, the man looped an end
under his arms, knotting it swiftly, flung the short coil to Bob and
lowered himself, disappearing into the water, his descent stirred up
mud, moiling the water. Down he went, hidden almost at once in the murky
disturbance.

Paying out the rope until it grew slack, Bob took a turn around a
rowlock, and they waited breathlessly. Some bubbles floated up and
broke. Then came a tug on the rope.

Curt, who had already come to the midships section, helped Bob tug and
haul in the wet manilla strands. The stranger came up through the murky
water, emerged, shook himself free of the liquid, caught the boat and
shook his head.

"Not in the cabin--only thing I can think of is--if he tried to jump and
got under the thing."

Very soberly the youths helped him back into the boat.

People were arriving on the bank, shouting to one another, calling for
information, shipping oars in boats. Al, having met several motorists,
had spread the alarm, and then had ridden on to telephone the police and
to report the crash.

Al, having returned, was in the second boat to arrive by the slowly
sinking craft.

Bob gave him a concise report while they pushed away from the place to
enable a deputy sheriff to take command and to jot down the stranger's
explanation and their own, from Curt.

"I wish you boys would row me across the little bayou, here," the man
said. Al had transferred to their boat by that time.

"Take me to that point, over there," the man added. "It's closest to
where I dropped my motorcycle when I saw the thing happen."

Bob nodded. The presence of the motorcycle beyond the lake, where it was
nearest to the road, explained why they had seen the man swimming toward
them. He must have heard and seen the airplane, watched its descent, and
then rushed to see what he could do.

"But won't the police want you to testify, or whatever it is?" asked Al.

The man shook his head.

"No," he replied. "If they do, they can find me soon enough. I'm off to
get into dry duds. I didn't waste time riding around the end of the
lake. I dropped my motorcycle and ran in to see what I could see." He
smiled, sadly. "I guess I was too late, even at that."

Thanking them as he climbed onto the rocky shore, he pushed the bow of
their boat into the stream again, and watched them turn in the still
water.

"You can tell the police I didn't think they'd need me right away," he
called. "I'm passing through this section, and I don't want to be held
up and kept here for any sort of investigation. You saw as much as I
did. Well--goodbye!"

He turned, and as they heard the "crash 'bus" arriving from the airport
in a nearby city of which they lived in the suburbs, Bob rowed his two
young companions back toward the airplane.

The police came, and many others with them and after them.

Preparations were made to drag under the craft, and to lift it, if
tackle could be gotten into suitable position, to see if any trace of
the missing pilot could be discovered.

Nothing further developed, however, and one of the "mechs" with the
airport 'bus told Bob it would be afternoon before they got the
monoplane out. The three comrades had given the police lieutenant all
the information they could. There was a healthy appetite making itself
felt among them.

"Let's go home," Bob suggested.

"Wait, all of you," urged the reporter for a small suburban daily. "I'll
make heroes of you yet."

Protesting that they had done nothing heroic and that they did not want
to be "put in the paper" for doing their duty, Curt and Bob refused to
answer any questions. The police, Bob said, might not want information
published. He did not know, but he would prefer not to talk. "Oh, I
see--there is a mystery, then!" the reporter declared. "Well, if you
won't talk--" he began to write swiftly.

"If we won't talk," Bob commented as the trio walked toward their
bicycles. "He'll write something anyhow."

"It's queer that there isn't any trace of the pilot." Al's mind returned
to the tragic part of the crash.

"Maybe he jumped clear, got away and went into the water, and then,
coming up, got to land. He may be on shore, somewhere, hurt, or too weak
to make himself known."

Curt's explanation renewed their hope.

"Let's hope it's that way," said Bob. "Well, we've got a long road to
breakfast. Mother will be just about wild. I left a note, but she will
worry about Al and me, just the same. If we go to the ball park and
don't get home within half an hour after the game, she frets."

"Excuse me, boys." A pleasant voice behind them caused the three to
wheel around. They saw a pleasant-faced man, beside an automobile,
parked close to the bicycles they were disentangling. "If you want to
get home in a hurry, pile the bicycles in that little comfort station
over there, and tell the attendant 'Barney' said to look out for them.
I'm from the aircraft plant, and as long as I can't do anything here, if
you'll hop into my car I'll ride you home while you give me the facts as
well as you know them about this smash. It's a bad thing, and I want to
get as straight as I can what happened."

They were very grateful to Barney, who neglected to furnish any other
name. He waited until they had stowed away the bicycles, and while he
drove them toward the village he questioned them rapidly.

"I think you are all very brave, and quick, and fine," he commented,
after they had, in turn, recited their adventures. "You acted splendidly
and I thank you very much."

Al looked surprised.

"We did our duty," he replied. "But why are you thanking us? I know it
was one of the Tredway airplanes because we were in it, with Lang,
yesterday on check-up. But who was in it, and what do you think
happened--really?"

"The owner of the manufacturing plant was in it," said Barney, very
soberly and sadly. "Mr. Tredway was flying it himself. He wanted to
deliver it in person--for a reason."

"For a reason?" Bob repeated, inquiringly.

"Yes," said Barney. "There is a mystery behind that crack-up--it's more
likely it's a 'washout.' Anyhow, there is something behind the smash,
and--I've heard there is a private detective, a Mr. Wright, at Forty-one
Elm. If you can tell me the quickest way to get there, I'll appreciate
it. I want to consult him--on this case."

Bob, Curt and Al stared.

"That's father!" said Al.

"Indeed! Then I am glad I offered you a 'lift.'"

They directed him, and eventually he drew up the car before the neat,
cozy cottage. Curtis, accepting the invitation to stay for their
somewhat belated breakfast, sat, with Bob and Al, in the cheerful
breakfast room, finishing up a stack of pancakes thickly syruped, when
Bob was sent for.

Returning, after a few minutes, he showed his younger brother and his
best friend a face of elation.

"There is a mystery, all righty," he declared. "And you're to come with
me----"

"Why?" asked Curt.

"Because," retorted Bob, "we're--in--on--it!" As the others jumped up he
added, "Father's home and he's taken a real air mystery case!"




                               CHAPTER IV
                        THE SKY SQUAD IS FORMED


Entering Mr. Wright's library, which the detective used as a reception
room for clients, Bob, Curtis and Al could hardly repress their
excitement. To share in the possible solution of a real mystery of the
airlanes was more than they had really dared to hope for.

Seated opposite Mr. Wright, smiling pleasantly, was the man who had
given no other name than Barney.

"Good morning, Mr. Wright." Curtis Brown greeted the quiet, but cordial
father of his two chums. Al added a salute to his father.

"Sit down," suggested the detective. Bob, Curt and Al ranged themselves
along the leather upholstered davenport at the side, where the light was
on their faces. Mr. Wright had his room so arranged that only his own
place beside the desk enabled him to keep his face in the shadow;
clients and other visitors had to show every expression in the light
from the two sunny windows.

While Mr. Wright seemed to be deciding how to disclose his plans, Curt
compared the two men.

They were of very distinct types. Fred Wright would make anybody think
of an ordinary, everyday business man, fairly prosperous, quiet in his
manner, affable and cordial in his speech. His calm, serious face was
neither severe nor too soft; and while its steel-gray eyes were kindly,
they could look through a person, it seemed, and find out, almost, what
that one was thinking, or, perhaps, trying to conceal.

Barney, on the other hand, made one think of a working man who had risen
to a position of prosperity and influence without being able entirely to
shake off his servile, unpolished manner. Although his clothes were
expertly tailored, he seemed a little ill at ease in them. What was
more, he gave the impression that he knew it!

He was a trifle blustery to cover his feeling of inferiority, Curt
decided; and he had a habit of interrupting when another person was
speaking. However, this might be due to excitement, Curt thought
charitably.

Glancing sidewise, he sensed that much the same comparisons were passing
through Bob's mind. Al gave no thought to character. His whole attention
was bent on the possibility of "action!"

Curt, who liked to look for good points more than for the other sort,
checked up Barney's dark eyes, almost black, and decided that they were
only serious because of the gravity of the situation. They could twinkle
with fun, he guessed; also, the mouth was so shaped that Bob admitted to
himself that Barney smiled oftener than he scowled.

"I have told Mr. Horton about you three young aviation enthusiasts,"
Fred Wright began. "Also I have explained that you used to be very fond
of 'detecting' in a decidedly amateurish way, of course." He smiled
across the desk toward Barney, whose face broke into a broad, pleased
grin, immediately suppressed because of the seriousness of his errand.

"I'll say we were amateurish," chuckled Bob. "Why, Mr. Horton----"

"Call me Barney--just Barney," the visitor interrupted.

"If you say so, sir. Well, Barney, then! We were crazy to be great
detectives, because father is one," he paid the compliment
whole-heartedly and only his father smiled and shook his head
deprecatingly, "but we let our enthusiasm take the place of brains," Bob
added. "I was not much help because I let vanity get the best of cool,
common sense----"

"I was a failure because I am too impulsive," contributed Al.

"I was so short-sighted, in my mind, that I forgot to look at the whole
of a case and pinned my nose down onto every little clew," Curt grinned
sheepishly, "so I kept going around in circles."

"All the same," Mr. Wright looked over at Barney, "in such work as boys
could do--they were a few years younger then--these three helped me a
great deal in handling two quite important cases."

The trio lowered their heads modestly.

"However," the detective continued, "they turned from being Master
Sleuths, as they termed themselves, to aviation----"

"Airboys!" chuckled Barney.

"Why, yes. That is an apt expression."

"But we didn't give up wanting to be detectives, really!" exclaimed Al,
earnestly. "We were looking for a way to mix the aviation with the
detecting--only we haven't gotten into either one."

"Then here's your chance." Barney said it very seriously.

"How?"

"Barney has brought me a very baffling case," Mr. Wright explained.
"Unfortunately, I am so deeply involved in another matter that I cannot
drop it."

"But you can give some time to this, you said." Barney was earnest.

"Not personally. That is, I shan't be able to investigate in person,"
the detective replied. "That is where our three assistants will
figure----"

"And be Airboys and Master Sleuths, both at the one time," Barney
interrupted.

"Hooray!" Al clapped his hand to his knee, unable to restrain his
enthusiasm. Mr. Wright, although with a tolerant, if brief smile, shook
his head at his younger son.

"This will be a serious affair," he stated, forcefully.

Al immediately became sobered.

"How can we combine aviation and detective work?" asked Curt, the most
practical of the chums.

"By going to the aircraft plant to work as mechanics' helpers, or
whatever positions Barney sees fit to put you in," Mr. Wright told them.
"That takes care of the detective work because you will have to keep
eyes and ears open and without appearing to do so."

"We can do that easily," said Bob.

"That takes no effort at all," agreed Al. His father, knowing Al's
expressive face to be easily read, made no comment.

"While you are at the aircraft plant," Barney took up the explanation,
"you will be working in and around the crates we are building, and you
will learn a whole lot about how an airplane is put together, what the
parts are for, and how they are assembled. That's the aviation part." He
emphasized the first syllable, making it "av-iation." "What do you say?"

"Hooray!" Al was irrepressible.

"Just show us the jobs!" added Bob.

"Of course we will be glad to learn." Curt was more sober. "That ought
to be one of the first things for anybody to do who means to be a
pilot." Mr. Wright nodded and Curt proceeded. "A good grounding in
airplane construction will be fine. But--for the detective part--I think
we ought to be very serious and consider it carefully."

"Indeed you should," agreed Mr. Wright. "There is a deeper mystery to be
solved than appears on the surface."

"I see that," agreed Curt. "And we must be sure that we will be a help
and not a hindrance to you----"

"Fine lad!" broke in Barney.

"Oh, we won't be a hindrance!" Al was almost bouncing on the divan
springs in his eagerness. "We'll watch, and catch whoever you want
caught--maybe learn to fly a 'crate' and hop off and fly after him and
ride him down and force him to land--and there you are!"

All the party laughed. Al, realizing his childish lapse into silly
chatter, laughed, finally, himself, a little ruefully.

"I see what Curt meant, now," he said, more quietly; but his excitement
was hard to hold. "But, anyhow, Mr.----"

"Barney!"

"Anyhow, Barney, we will try to help. We can learn about airplane
construction, and that will be fine; but we will give all our minds to
watching and listening and doing whatever is wanted of us--we ought to
form some kind of club or order, so we would have a head to get orders
from father--especially if he is too busy to take part himself."

"That's sensible, even if it does seem boy-like to want to have a secret
association," said the older detective.

"Then let's call ourselves what Barney called us--the Airboys."

"I don't like that very much," objected Bob.

"Well, then, you pick a name."

"I think the game is more important than the name," observed the older
detective.

"Oh--but with a good name for our band, and a chief, we can know where
we are," urged Al.

"All right," said Curt. "Let's humor the youngster!" Al grimaced at him,
but subsided as Curt went on. "We are detectives as well as airplane
enthusiasts. Why not combine the two in the name of the order we are to
form--something about the sky, and something about a police--detective
squad----"

"You've hit it!" Barney interrupted.

"Hit it? How?"

"Sky Squad!"

"Crickety Christmas!" Curt was as enthusiastic as Bob and Al became on
hearing the words. "That's it!"

"Very well," Mr. Wright was patient, but a little annoyed. "That being
settled, we can take up the important matter of--the case!"




                               CHAPTER V
                            A DOUBLE PUZZLE


Barney stood up and looked at his watch: also, he frowned a little.

"I wish we didn't have to waste the time," he objected. "I've went
through it all with you, Mr. Wright, and I wanted to take these lads
along back to the plant in my car. I wanted to make it look like I just
happened on them at the accident--the--well, the accident, and found
they were interested in av-iation and brought them back to fill a couple
of places in the plant."

"But how can we solve a case if we don't know what it is?" remonstrated
Bob.

To that Curt nodded and Al bobbed his head rapidly.

"As a matter of fact," Barney turned to Bob, "I think you would do a
whole heap better if you went in to it blind, sort of. If you know all
about it, you'll go out to the plant, all serious and acting like judges
or detectives. If you take it the way our youngest friend, Al, does--as
a sort of lark--you won't be suspected so quick."

"There is something in that," Mr. Wright admitted. "Al's face is apt to
give him away if he thinks it is really serious. Perhaps----"

"But all the same, Father," Bob declared, "how will we know what to
watch for? How will we know what to report?"

"Watch anything you see. Listen to whatever you hear. Report the whole
business!" Barney exclaimed.

"That does seem wise," Mr. Wright agreed, rising also. "Boys, let's
emphasize the Sky part of your order, and let the Squad side rest
awhile. Barney wants to get back to the plant--he is the Manager, I
meant to explain. He ought to be at the end of a telephone wire. Let's
say only this: There is a double mystery. First of all, valuable parts
have been missed, from time to time, from the plant. That is a minor
matter, at present, but your first puzzle is--where have the missing
parts gone and who took them? But, as I said, that is a minor affair,
because----"

"Somebody has tampered with some of the finished crates," broke in
Barney. "Why, and who--that's the second puzzle!"

"Suppose you take that as enough for the present," suggested Mr. Wright.
He turned to Barney. "Now these three young lads are alert, obedient,
and they will follow instructions to the letter, if you give orders," he
explained. "You have already seen how----"

"How quick they are in emergencies! Yes sirree! All right. I know I can
depend on them. Sorry you can't investigate in person, Mr. Wright--but
maybe this way will work out best. Anyhow, nobody at the plant will get
suspicious of these boys. They won't have the brains of older men, like
you and me, but they will have quick eyes and wide ears," he laughed,
and beckoned, "come on, lads."

A little disappointed, feeling that there was more behind the mystery
than Mr. Wright had disclosed, but accepting his "lead," Bob, Al and
Curt caught up their caps from the hall rack and followed Barney into
the car.

As he drove toward the large manufacturing buildings, the administration
offices and the assembling rooms, "dope" rooms and testing field that
formed the Tredway Aircraft Corporation plant, Barney kept away from
talk about the mysteries.

Instead, he questioned them about the plan for their new organization,
suggested secret codes, urged them to elect a "Boss Pilot" and really
fired their imaginations to such a point that when they came in sight of
the aircraft plant they had almost forgotten their disappointment at not
being taken fully into his confidence.

"Well," he said, when they turned in at the gateway in the high board
fence that kept curious wanderers out of the grounds, "here we are, Sky
Squad--ready to begin to learn how a crate is started, what the design
means, and why certain things have to be planned for--and then, what
goes into construction and why, how she's put together, and then, how to
fly the finished crate."

Sensing from his tone that he wanted them to concentrate, at least
outwardly, on airplane construction and to let the other part of their
activity be kept quiet, the three comrades agreed by assuming an
interest that was by no means hard to pretend, when he took them into
the offices, introduced them to some of the men working there, and
explained that he was going to put them to work "to learn to build
crates from the prop to the tail skid." Barney, on the way, had learned
their special interests. Therefore he put Bob into the engine assembling
division where he could learn more about radial engines and the
experiments being conducted with oil-burning types. Curt, who was
methodical, cool and careful, was assigned to work, at least for awhile,
in the wing assembling rooms. Al, being rather young for too much
technical understanding, was assigned as helper to a "rigger," who had
been grumbling for some time at the laziness of his present assistant.

Everything was so new and so interesting that the trio forgot the
seriousness with which Mr. Wright had assembled them that morning; but
as they rode their bicycles toward home at lunch time, Bob imparted
information that both startled them and turned their minds back to the
serious business really underlying their work.

"I heard some talk, this morning," Bob told his brother and Curt. "It's
serious, fellows! Missing parts aren't half the puzzle--and tampering
with airplanes isn't all the rest."

"What is, then?" demanded Al.

"They think, in the wing assembling room," Curt put in, "that the
airplane fell this morning because something went wrong with Mr.
Tredway. The plant owner was delivering that craft himself. They all
argue that he must have had a heart attack, or something of the sort,
because the airplane was tested and gone over thoroughly. They say he
must have been taken sick and lost control. Is that what you mean?"

"I heard some 'mechs' saying they think he deliberately made away with
himself because of money trouble or something they don't know about,"
added Al. "Maybe trouble with his family, one says."

"That isn't it," Bob said soberly.

"What is?"

"The talk in the engine plant was that some enemy deliberately tampered
with that airplane because--because he knew the owner was to fly it."

"But--" Curt was astounded, "but, Bob--that would be----"

"Yes," admitted Bob, very gravely, "yes--it would!"

"That makes the puzzle about missing parts and the rest unimportant,"
Curt commented, thoughtfully.

"But it still gives us two puzzles to solve," Al began.

"Well," corrected Curt, "not two separate puzzles--but a double puzzle,
all the same."

"A double puzzle? I don't quite see----"

"It's all one problem," Bob explained to his younger brother. "But it
has two sections. First--was the airplane tampered with as an act
against the aircraft corporation or against Mr. Tredway in person?"

"And second?----"

Al did not let Curt complete his deduction. Al had one of his own.

"And second--who did it?"




                               CHAPTER VI
                         SUSPICION AND SUSPENSE


Full of their horrifying suspicions, Curt and Bob rode on. Al turned off
on a side street to deliver a parcel at the home of his new boss,
"Sandy" Jim Bailey, the rigger. Al wanted to "make himself solid" with
the sandy-haired man whom he already liked and whose grumbling was over
now that he had, as he said, "a willin' and brainy helper."

Curt ate lunch with Bob. Both were disappointed when Bob's mother told
them that his father had been called out of town on his case, accepted
earlier.

Riding back, to rejoin Al, who was waiting at the gate of the plant
ground, Bob accosted his brother in some surprise.

"Aren't you going to have lunch?" he asked.

"I had it," Al told Bob and Curt. "I delivered that package for Mr.
Bailey, and met his son, Jimmy-junior. He's just about my age, and an
awfully nice fellow. He invited me, so I stayed." He dismounted and set
his wheel inside the enclosure. "You ought to see the model airplanes he
builds. They're great!"

"Well, we can't stop to talk about them now. Mr. Barney Horton left word
with the gate-man we are to come into the administration offices to see
him." Bob led the way as he gave the information.

"It will give us a chance to look over the office staff," Curt
explained.

"Be careful, Al," his brother warned him. "See that you don't let
anybody guess that you see any suspicious things. You show everything on
your face, you know."

"All right."

Barney greeted them in his private office and introduced them to Mr.
Tredway's partner, Mr. Parsons, who was there.

If his manner was somewhat abrupt and his mind preoccupied, Bob made
allowances for that. The man was overcome by the mishap and its sinister
outcome.

His restless, seemingly uneasy, and almost furtive actions, however,
were not so easy to account for. He seemed unable to meet the eyes of
the comrades directly, and appeared to be nervous--even more than the
circumstances justified, Bob thought.

Almost on top of the introductions he hurried out, "To get out there
where the airplane cracked up and see what's what!" he explained.

"He takes it mighty hard, he does," Barney told the youths. "No wonder.
He's Mr. Tredway's partner."

"But there isn't any real certainty that anything terrible happened to
Mr. Tredway," asserted Curt. "He might have jumped clear."

"Yes, and maybe he was hurt, and managed to swim off to some part of the
shore and wasn't able to go any further. They haven't searched every
possible spot have they?" Al was hopeful.

"I'm afraid they have," Barney replied. "Furthermore, there are so many
soft, muddy sink-holes in Rocky Lake----"

"Do you agree with what the people in the plant are saying?" Al asked.

"I don't know, my lad. You see, it's a good idea, having you here. When
I'm around the people shut their mouths. But you hear things. What are
they saying?"

"They think it's something worse than missing parts and damage done to
the 'crates'," Al answered and explained, calling on Curt and Bob for
their versions of the talk.

"Hm-m-m. Well, Al, I think--if I were you--I wouldn't listen to the talk
around the plant too hard. Pick it up, of course, but don't go making
any theories of your own out of it." Barney explained that people buzzed
like a lot of flies every time anything happened, and that many of the
less sensible ones, liking to be "in the limelight," worked up almost
idiotic theories. Usually, if they were accepted, they led to unjust
suspicions, he argued.

"Those scatter-brains only want an audience to listen to them," he
declared. "I'd advise you to listen and let it go out the other ear.
Otherwise you may get off onto the wrong notion. Better watch out for
suspicious actions, and leave the theories to Mr. Wright."

"But he's away," argued Al.

"Only temporary, I guess. Anyhow, you can tell me what you hear and see,
and let it go at that. I'll communicate with Mr. Wright, and if he
thinks there is anything as bad as you say, I can tell you how to go
on."

"All right," agreed Curt.

Bob and Al added their own agreement to the suggestion.

The designer and the engineering staff were introduced and several hours
were devoted to discussions between them, for the benefit of the trio,
about airplane design and the things that had to be taken into
consideration.

"If my young friends are going to learn airplane building," Barney
asserted, "it will be better if they know how important it is to figure
stresses, safety margins, stability and so on, before ever a design gets
on paper."

"I thought all those things came out in the tests, after the airplanes
are built," Al contributed.

"Oh, no," the designer said. "The tests show us how well we figured and
how good the designs are that we created. But we work everything out up
here before ever an engine part is cast, a fuselage built or a wing
assembled."

"Any other way would be hit or miss," Bob agreed.

While they learned the many sections into which an airplane design is
divided, and how carefully every curve, streamline, distribution of
weight, lift of wing and drag of body must be calculated, Bob decided
that no one in the office--at least no one with whom he came in
contact--was acting in any suspicious manner.

Able to do nothing about the accident, the staff went on with its
accustomed work, sadly, more seriously, to be sure, but steadily.

However, when Bob returned to his engine assembling work, he met a new
character, and one of whom he at once formed an unsatisfactory opinion.

By association of ideas Griff Parsons fell under his suspicion because
the youth, about eighteen or nineteen, was the son of the man Bob had
seen in Barney's office--Mr. Parsons. Griff, whose handclasp was flabby,
whose eyes were even more shifty, whose manner was still more uneasy
than his father's had been, did not impress Bob favorably at all.

He had something on his mind, Bob decided.

Assigned by the engine department foreman to help Griff fit piston rings
onto the small pistons, to fit the piston assembly into the cylinders,
before the final assembly was made, Bob learned much, and somewhat more
about Griff than about the nice adjustments of machinery.

If he turned suddenly, Griff almost jumped, having hard work to control
his muscles.

When he spoke of the morning's accident, Griff, with a scowl, told him
to "Keep your mind on what you're doing! That other ain't any of your
business!"

Bob had hard work not to show his antagonism to the gruff, snappish
young man; he was grateful when a summons took him out into the yard.

"I think it is a good idea to have you fellows treated as though all you
are here for is to learn about airplanes," Barney greeted him. "Your
Cousin Langley is going to take up the sister ship to the cracked up
Silver Flash, this afternoon, and I'm sending all three of you with him.
It will give you a chance to understand what the designer told you about
how carefully he had estimated the shape and weight of the new type
longerons and how some mistake that he hasn't been able to figure out
yet makes the new crate tend to slip off sideways too easily. Langley
will show you how he checks and reports, and then you will understand
how every one of us works in harmony with every other one, to build our
ships airworthy, safe and steady."

When they joined Lang, who was busy checking his dashboard instruments
as the engine warmed up on the line, Bob, Curt and Al did not hook
safety belts on. They had every confidence in Lang's ability to handle
the ship, and they were more anxious to be near him so they could talk
than to sit along the cabin sides unable to communicate their news to
him over the roar of the engine.

As soon as Lang sent the powerful engine into speed, racing down the
runway into the wind, lifting the elevators to catch the propeller blast
and tip upward the nose, then flying level, just above the ground for
those essential few seconds in which flying speed was regained before
the climb, Al opened the conversation.

"Lang," he cried, pitching his voice to offset the noise about them,
"did you know what they are saying about the accident?"

Langley nodded.

"This seems to be a test flight," he said. "But I'm really flying over
to the airport, in the city suburbs--Barney wants you along to scatter
and pick up talk there."

"What's the airport got to do with the mystery?"

"Barney thinks that mysterious crate we saw in the field might have
something to do with it," Lang responded to Curt's question.

"But Barney told us not to go building theories," Bob objected.

"He's older, and better able to see things clearly," Lang reminded him.
"So we will climb pretty high, as if for test dives and slips, and
skids, and barrel rolls--you'd better be sure to snap your safety
belts--not right now, though. This crate slips pretty sharp. But----"

"I think we're wasting time," declared Bob, "flying to the airport."

"Why?" asked Lang.

"In the first place, the airplane was carefully hidden. No one at the
airport would know anything about it. In the second place, I can't see
how it could link in with the crash----"

"Unless its pilot was higher than Mr. Tredway, and flew over him and
forced him down--" Al was excited at his deduction. He felt puffed up.

"We would have seen him," objected Curt, crushing Al's inflated vanity.

"By the way," Bob broke in, "let's talk about something else. If Barney
sent you for information, that's that. Never mind what we think. What I
want to do is to get a line on that fellow named Griff--Griff Parsons."

"Why?" Lang swung in his seat, catching the shift of the crate with
almost automatic movements of stick and rudder bar. "What about him?"

"He's the son of the superintendent, isn't he?" asked Curt.

"Yes," Al broke in, "and what's more, I suspect that 'super.' He looks
like the sort who could do tricky things. Did you see his eyes?"

"Yes," agreed Curt. Lang cut the motor, and glided gently, to hear
better.

"But what has that to do with Griff?"

Bob, surprised at the sharpness of Lang's tone, frowned.

"He looks like the same type as his father--same shifty eyes, same
restlessness--furtiveness!"

"Say! See here!" Lang became suddenly angry. "You let that young man
alone and keep your unfair suspicions off him."

"Is that so?" Al was angry, too, all at once. "Who are you to give us
orders?"

"I'll let you know who I am if you go on suspecting innocent people.
What's more, I'll have Uncle Fred yank you out of there so quick----"

"What makes you so hot under the collar?" demanded Bob. "What is it to
you if we suspect Griff? Is he an angel that we have to keep our minds
off him?"

"He's a mighty good friend of mine!" snapped Langley.

All of them were angry. Curt, not related to the others, felt that he
ought to intervene between the quarreling cousins, but something in the
unreasoning fury of Lang's next words stopped him.

"See here!" Lang forgot he was piloting an airplane, and swung around on
his seat, his face working. "If you keep on, if you bother Griff, or try
to trail him, or anything--I'll have Uncle Fred yank you out of there so
quick----"

"Oh! Look out!"

Forgotten, the airplane, with no guide, answered automatically to the
thrust of Lang's foot on the rudder bar as he whirled on his cousins.
The shift of the rudder swung the nose, and Lang's instinct made him
operate it to make the ailerons bank the ship, but she had almost lost
flying speed, the all important velocity which gives the wings lifting
qualities.

Sickeningly the airplane tilted. Al, Bob and Curt, not strapped fast,
tumbled sidewise, and the unstable craft tipped down.

Abruptly, realizing the slip and the danger, although they were quite
high, Lang "kicked rudder" sharply.

To his dismay, there came a dull, snapping thump and one end of the
rudder bar worked free.

The cable had either come loose or had snapped!

And, with its unstrapped occupants in a huddle, on the side which was
lowermost, the lower wingtip turned straight downward, the other pointed
toward the sky, the windowed sides were in the position of floor and
ceiling--and the airplane began to fall!

"Three thousand feet," Lang's eyes consulted the altimeter. "Three----"

Momentarily he lost his "nerve" and faltered.

Bob, on the instant, acted!




                              CHAPTER VII
                         IN THE FALLING 'PLANE


In an emergency, thoughts leap through some minds quicker than lightning
crosses the sky.

Bob's mentality was of that type. Whether his mind worked through what
is called instinct, or whether he put together many things he had
learned about airplanes, or whether he worked through a chain of
reasoning from beginning to end in a fraction of a second does not
matter.

The important thing was his action.

In an airplane which is falling with wingtips toward sky and earth, the
ailerons which usually tilt it are practically useless, because it has
no forward movement sufficient to bring the air against the leading
edges of the wings for lift, or to press against the ailerons to cause
them to function properly.

Furthermore, when the ship is falling "on its side" the elevators which
in level flight serve to lift or to drop the nose, are no longer
elevators; they, because of the position of the ship, are really the
rudders, while the rudder, because it is then parallel to the ground,
assumes the position and functions of the elevators.

But Bob knew, in a flash, from the action of the ship, from the free
movement of the rudder bar, that the rudder cable had come loose or had
snapped.

Bob knew, furthermore, that unless he could drop the nose, "give her the
gun," and thus--by partly diving instead of falling sideways, and by
partly using the propeller pull--could regain flying speed, Lang could
not get the craft under control and save them from a crash.

There were seconds, not more, between them and eternity!

That rudder must be operated.

It must be done before they came too close to earth to make the
maneuvers, necessary to a safe landing, possible.

Even as he called to Lang, "Give her the gun!" his hand smashed through
the thin side of the cabin wall, down where it came together with the
sturdy, but light plates of the flooring.

Because the airplane fell on its side, the side he smashed was under
him, the flooring was at his side, acting as the sidewall.

He knew that if the lower of rudder cables in the ship's present
position was broken he could get it there; if the upper one was severed
its end would have dropped down, perhaps caught on a longeron or on a
longitudinal fuselage brace; he might be able to catch hold of it.

It took but a second to thrust his hand through the cabin wall, to grip
the edge of a floor plate, to rip it from its temporary fastenings which
were not completed until the tests made it sure that no further
adjustments under the flooring would be necessary.

Thus disclosed, he could see the under framework of that part of the
fuselage.

Braced so that his body would not crash down through a window, he
looked, and grappled for the cable end. His fingers touched cable!

For all the exigency of their desperate situation he tugged very gently
and was glad. That cable was fast! It might lead to the elevators, the
ailerons. Anyway it was not the right strand.

Again he felt under the edge of what was in the ship's position, the
plate above the one ripped away. His fingers touched a loose strand.

"We're all right!" he panted, grasping the plate and tugging it partly
free so that his arm could go further in and secure in his gripping
fingers the loose cable end.

In the brief time that this had taken, Lang had obeyed the call for gas
to be fed to the engine. Idling, it roared into its power pulsations.

There was an instant of fear in Bob's mind.

If the cable he held were pulled and it depressed the rudder, which
would act in their position as an elevator or "flipper" acts, all would
be well. In that case, the propeller blast striking the rudder airfoil
would push the nose downward, and the ship would begin to dive; then the
air, rushing against the leading edge of the wings, would cause them to
be operative, even in their sidewise position, and with the dive and the
engine pull giving flying speed, they could then maneuver.

But if the rudder went upward, it would lift the nose. Already deprived
of all but the little speed the engine had picked up, the blast on the
rudder, lifting the nose, would cause another stall, and they would
perhaps fall too far to get the other side of the rudder cable before he
could help it.

"I've got the end of the cable," he cried. "Set yourself, Lang!"

Lang, with a swift glance toward the windows, which faced the earth, saw
the ground seeming to leap upward toward them. Above was the silent sky.
There was a little margin of time--if----

"Pull easy!" Lang shouted.

"Pull easy!" Instantly Curt relayed the message.

"Easy!" cried Al.

Bob tensed his muscles, braced himself, gave a gentle tug and held it.

The nose lowered.

"Hold it!" shrilled Al, relaying Lang's relieved cry.

The rudder had sent the nose a little downward, the drop changed into a
dive.

"Can you pull the rudder further?" The message came swiftly from Lang,
through Curt and Al, to Bob, almost out of one mouth before the other
said it, so quick was the response.

"Yes!" Bob did so.

Slowly the ship swung onto a more level keel, and while Bob clung with
fingers that were growing numb from his excitement, the ship got flying
speed, in a sort of descending spiral, the elevators could again be made
to lift the nose as flying speed was attained, and the ship was in
control.

The signal to ease off did not come at once. Lang preferred to hold his
present bank and circle, while he looked over through the lower cabin
windows to sight their position.

In that brief time Curt, also keyed up, had located the loose end of the
cable that led from the rudder bar; with a piece of strong twine he made
a splice, securely reaved onto the loose end, led it to the free end in
Bob's fingers, and, since the rudder was hard down and could be held
there by grasping further along the cable, Bob shifted his grip until
Curt was able to get his twine, doubled, fast on that part of the cable
also. Then, while Lang held his rudder bar steady, Curt tightened gently
until the ends of the severed strand were almost touching, made several
knots that could not slip--and the entire control of the ship was in
Lang's hands again!

They did not feel like going on to the airport, but Curt, always cool,
generally far-seeing, urged that they do so.

"If we go back, we'll have to tell about this, and create new excitement
and talk," he counseled, and Lang saw the good sense of the idea.

"We'll go on, and land at the airport," he agreed, above the sound of
his motor. "After we get over our excitement we can think better."

When they got there, and Lang telephoned the aircraft plant, the trio,
outside the booth, heard him ask for Griff.

Moodily, sorrowfully, with common consent, they moved away.

One and all they linked Griff's uneasiness and Lang's curious anger and
immediate call to the one he called "a very good friend."

It was bad enough to suspect Griff. But Lang--Bob's cousin----

That was dreadful!




                              CHAPTER VIII
                            WATCHFUL WAITING


Moodily walking back toward their airplane, around which a group of
handlers and mechanics watched one assigned to make sure the cable
splice was entirely safe, Curt spoke quietly.

"Bob, maybe we should have waited to hear what Langley said to Griff."

"No!" Bob was almost snappish. "No!"

"I hate to suspect your cousin of anything wrong," Curt assured the
brothers earnestly.

"Not any more than I hate it," Al retorted. "But you've got to look at
what you see and hear what comes to your ears."

"All the same," counseled Curt, hoping to lighten the burden of
unhappiness for his chums, "I'd go slow. You know--they may be just
friends, close ones. There may not be anything wrong about Griff. We are
likely to be suspicious, because that's what we are there for."

"But look!" objected Al. "The cable snaps. Now that's almost a
spick-span new crate. That cable ought not to fray apart--it could never
wear so soon. It was--filed or scraped."

"But that doesn't involve Griff," urged Curt, hoping, if he lightened
their suspicion of Griff the cousin who was his friend would be less
suspected. "He works in the engine department. Anyhow, he knew his
friend, your cousin, would fly the 'plane. He'd never----"

"Sh-h-h!" warned Bob.

Langley, looking very glum, came up to them.

"I talked to Griff," he said. "Told him what had happened. He was
flabbergasted."

"You ought to have reported to Barney--or to Mr. Parsons," Bob declared.

"Why did Griff have to know anyhow?" Al was impulsive and did not care
if he started a fresh quarrel or not. The conclusion he jumped to was
that an angry Langley would disclose "secrets."

"I wanted to warn him against--you!"

Langley walked away. But they did not let him get far ahead of them as
they approached the airplane.

The mechanic who had been in the cabin greeted them.

"Funny about that cable," he stated. "How did it ever get so much use
that it wore through? You must kick rudder every two seconds."

"Was it worn through--or--" Al began. Curt prodded his ribs very
sharply. As Al became quiet Curt asked a louder question to distract the
man from pursuing that "or--" and learning their fears.

"Or did it break at the rudder bar?" he asked.

"It chafed against the transverse brace it ran under," the mechanic
responded. "They ought to have an eyelet or something for a guide--a
small pulley would be best, with an eyelet to keep the cable from
slipping out of the groove and chafing on the solid part of the pulley."

"We'll report that," said Curt. "A rudder is pretty important."

"I'll say," replied the mechanic.

The plates had been fastened back into their light frame, being of
sturdy construction and not permanently attached, they had come away
clean and were put back easily. Only the cracked hole in the panels gave
outward evidence of the recent near catastrophe.

"Suppose we let on that was an accident, that I put my foot through the
panel," suggested Curt. "Repairing it only means putting in a new
section there--it ought not to cost much and I have some money in my
savings account to pay for it."

"Let's all put together," urged Al.

"Why not tell the truth?" snapped Langley.

"Don't you want to find out who endangered you and the rest of us?"

Lang considered Bob's sharp phrase. "Yes," he said finally.

The best way to do that, argued Curt, was by watchful waiting, not by
putting the possible malefactor on his guard. "They could," Al declared,
"see who makes the repair, and I can watch, being out near the 'planes,
and see if anybody takes a special interest in the floor and the
cables."

Langley agreed rather bruskly and went off to take up his inquiries
about the brown airplane they had seen in the field.

"Watchful waiting!" repeated Bob, thoughtfully. "That's a good slogan.
Let's 'watchful wait' to see what Griff does--and how Lang acts--and if
either of them acts queerly when they are with Griff's father."

"Just what makes you suspicious of him--the father?" Curt asked, more to
check up his own theories than for information. "He's Mr. Tredway's
partner, you know."

"I suspect him," Al declared, "because he's the kind that looks
suspicious, with his quick action and his sharp talk and his shifty
eyes."

"And Griff is exactly the same in every way," supplemented Bob.

"Then we have two suspects to keep tabs on," agreed Curt.

"Three," corrected Al.

"Let's leave Lang out," urged Curt.

"All right--we won't watch him. But it's bad, because we can't talk over
plans and tell him everything. There will be--a--a----"

"Strained relationship," suggested Bob.

"Yes," agreed Al.

"Well, pretend to be the same as ever, but keep your ideas to yourself,"
Curt begged. "And--we'll be watchful waiters."

During the next week that was the only policy they would have been able
to adopt. Nothing happened at all.

Al still carried parcels, on occasion, for rigger Sandy Jim Bailey, and
improved his acquaintance with Jimmy-junior.

Mr. Wright's absence from town during the entire week prevented them
from consulting that detective. The comrades were thrown on their own
resources.

"I don't see that watchful waiting has gotten us very far," commented Al
as they rode home for lunch, Curt with the brothers, at noon on
Saturday. The day's work was over.

"We know a little more than we did," Curt reminded him. "I've had talks
with some of the boys I know, and I've found out that the ones Griff
associates with aren't thought well of. And Bob has trailed him, several
evenings, in spite of Lang's warning to Griff, and Bob has told you that
Griff always gets away on his motorcycle and goes somewhere that we
can't locate yet. But we know his character isn't very high class, and
his father still acts uneasy and preoccupied. So we have gained that
much."

"What good is it?" Al was unconvinced. "It doesn't say what happened to
Mr. Tredway. It hasn't told us who is taking airplane parts. It doesn't
explain who tampered with the rudder cable in the Golden Dart--or why."

"No," Bob admitted. "That's true, it doesn't. But it's the best we can
do, for the present. And we never know when something may 'break.'"

"Let's keep on learning airplane technique," suggested Curt. "We know
we've gained there, anyhow."

"Yes," Al nodded. "I can name the different parts of a biplane without
stumbling over any of them." He did, "--fuselage; engine; propeller;
upper and lower wing; cockpit and its cowling; struts and landing and
flying wires; stabilizer, fin, elevator, rudder; ailerons; tail skid;
and landing gear that Sandy calls the 'trucks.'"

"Correct," agreed Curt. "And they comprise five groupings, each one
having a special purpose--the fuselage, the supporting structure for
everything else. Everything is attached to that. Then----"

"The second group," Bob cut in, "is the supporting surfaces, the wings.
They sustain the whole weight in the air, and the flying wires take the
lift of the wings as the air sustains them, and communicates it, with
the struts helping, to the body.

"Well, in a way," Bob changed the statement slightly. "The flying wires
are to take the stress, and if it wasn't for them the wings would tilt
up at the ends or tips, like a 'V.' The flying wires take the stress in
flying the same as the landing wires take the weight of the wings in
landing; without the landing wires, when the ship came down the wings
would crumple down over the crate like the two slanting sides of a tent
or like the 'V' upside down."

"Yes," Al showed his knowledge, "and then there is the control group,
the ailerons at the backs or trailing edges of the wings, to be moved
upward or downward, to tilt the ship; and the rudder, to turn it
sideways--and if it's flying on its side the rudder is performing the
office of the elevators and they of the rudder, because when it's flying
level the elevators are to tip its nose up for a climb or down for a
glide; then there's the fin and the stabilizers that give it balance and
help to hold the whole ship in whatever position it is placed by the
movable controls I just mentioned."

"And with all those you have a glider," agreed Bob. "The engine, and its
'prop' are for motive power, and the landing group, either wheels for
the earth, or pontoons for the water, or both, combined, in an
amphibian, for land-and-water use----"

"We know some things," agreed Curt. "But we don't know where Mr.
Tredway's body went--or----"

"What Griff is going to do with his Saturday afternoon," commented Bob.
"I'm going back to the plant, and pretend to finish up work, and see
what happens there while it's supposed to be closed down."

The others agreed. Something might "break." Actually, something did!




                               CHAPTER IX
                            STRANGE ACTIONS


Although the aircraft manufacturing plant observed a forty-four hour
week, closing down on Saturday afternoons, when the three members of the
Sky Squad returned, about two o'clock, they were somewhat startled to
discover that their "suspects" were there.

Bob, entering the engine section, discovered Griff.

The youth was surprised, "caught in the act!" mused Bob as he saw the
youth, with furtive, hasty actions, completing the wrappings of a
smallish package which he hurriedly slipped into his coat as he turned
aside, trying to conceal his action from Bob and then, noting that he
was caught, trying to pass it off as an ordinary action.

"So that's where some of the smaller parts are going," Bob concluded,
pretending not to be aware that anything was wrong.

"Hello," he greeted. "I thought I'd come back and take that model engine
apart, while no one was here to bother me, so I can get it straight in
my head just how the valves operate."

"Yeah?" Griff was inclined to be gruff, and as he tinkered around trying
to pretend to be busy, but, to Bob's notion, watching the member of the
Sky Squad, the latter gave every impression he could of ignorance that
he was being supervised, studied, observed.

Had Griff been intruded upon before he finished what he had been doing?
Bob wondered as he took off the cylinder head of a small, roughly
assembled model of a new design for a Vee-type motor they were working
on. It appeared that Mr. Tredway had been "all for" the newer radial
engines, while Mr. Parsons exerted all his influence to introduce the
model in which the cylinders, in line, came together in a slanting
fashion, like a "V" at the crankcase jointure.

Bob took out pistons and pretended to examine the crankpin assembly.

Griff watched covertly and appeared to be exceptionally uneasy.

Curt entered from the wing assembly rooms.

"Hello, Griff." He nodded, paid little attention to Griff and went over
to Bob.

"Interesting?" he hinted. Bob nodded, and began to explain the parts.

"I see." Curt, bent close, whispered his next words. "Lang is out in the
yard, working on the Golden Dart. He has the plates out and he is----"

As he spoke Lang came in.

"Say, Curt," he called, "run up to the offices, and if Mr. Parsons or
Barney is around, get me a new--er--length of cable, will you?"

"Will they give it to me?"

"Sure."

"Supposing there's nobody around. The office is closed."

"Go to the supply room, on the ground floor. The watchman will let you
get what you want. All you have to do is to write out a requisition form
and put it on the spindle on the desk. You'll see it."

"Can you get supplies as easily as that?" Bob asked.

"Surely! Why not?"

Curt and Bob made no comment. The former went to execute Lang's request.

In the offices, as he neared the open door of the bookkeeper's little
cubby of a room, Curt heard two low voices. He hesitated. He was close
enough to be able to recognize in the bent figure leaning over the
other, with his back turned, the peculiarly checked brown suit which
identified Mr. Parsons.

Evidently neither the partner nor his companion heard Curt, so absorbed
were they in some discussion or comparison of figures.

Curt, wondering why they were so engrossed in that work when the office
was closed, and so absorbed that they had not heard him--he had not
tried to snoop or to creep along the hall!--decided that it must be
legitimate business, and that he would not disturb them.

He went on beyond to the rear stairway and down, looking for the
watchman.

Al found him there.

"How do you get into the supply room?" asked Al.

"That's what I'm trying to do. What's that you're carrying?"

"It's an earth inductor compass," Al explained. "You heard Sandy hail me
as we came in." Curt nodded. "He stayed on to check up my work," Al
informed him. "I'm pretty raw, you know, and Sandy is so good-natured
that he didn't want to see me get into any trouble. I was helping one of
the mechs this morning"--he had already picked up some of the slang,
shortening "mechanic" as did those in the plant--"and Sandy was going
over the instruments I had installed. That Golden Dart is going to be
used for an overseas hop, he says--and--" he went close to Curt, "Curt,
I think Sandy has helped us to get a line on somebody else to
suspect--about the stolen parts, anyhow."

"How?"

"He called me over and told me, in a joking way, I had a lot to learn.
And then he asked me if I knew anything about how this new type compass
operated. I knew a little, but not much, and he showed me how little I
knew. Curt--" he was very serious--"this is an old, broken thing. Look!"

He indicated the failure of the parts to operate correctly.

"If we'd let that get to the checker, Monday, I'd have been suspected of
getting away with the regular, real one. This must have been substituted
by the mechanic who was on that job--the one I helped. Or else it was
given out by the clerk who has charge of this room. Anyhow, Sandy says I
ought to put in a requisition for another one, and then he is going to
help me keep an eye out to see what happens on Monday. He wants to help
us. I saw he was so afraid I'd get the blame, and he's so mad about the
way things are being taken that I let him in on our secret----"

"About being detectives?"

"Well, only as far as saying we were crazy about aviation and had formed
a sort of order we call the Sky Squad, and naturally, being honest, we
saw how things were going here and wanted to do what we could to
discover who is taking parts."

"And what did he say about it?"

"He said not to be too hasty to jump to conclusions. He told me that
this substituting of the old inductor compass looked like the work of
the mech, but it could be the supply clerk, or, maybe, somebody outside
the plant entirely who had sent it in, boxed, in a new consignment. He
said the safest way would be to put in a new requisition, then we'd see
who acted guilty when it was discovered. If the supply clerk is guilty
he would never mention it for fear of being caught. If the mech is the
culprit, the clerk will raise a howl about the exchange. If they are
both innocent, you'll hear from both of them, and we can trace it to
somebody who sent the consignment."

"Good stuff!" agreed Curt. "But didn't the mechanic notice it was a
broken model of the compass?"

"He gave me the instructions how to assemble it and told me to be
careful, and then went over to work on that small speed craft that Griff
is testing out. Griff called him, so it looks all right. If the mech
noticed this old compass, before he went home, he'll tell me, first
thing Monday. If he knew about it and had taken the other, the good
one----"

"He'll lay low. I see."

The watchman, making his rounds, observed the pair. Readily enough he
admitted them to the supply department. Either he was of too
unsuspicious a nature, being rather dull, to wonder or question; or he
had been told by Barney that the youths were especially privileged. In
either case he made no comment as they found the cable Curt wanted for
Lang and the several extra inductor compasses, neatly boxed, among the
stacked instruments in the shelves.

Making out two of the slips he saw in a pad, and fixing them on the
upstanding spike of a file, Curt handed Al his box and with the cable
went to find Lang.

Handing the strand to his chum's cousin, Curt decided to return to the
office building to see what he might see. The excuse that he was
studying the blue prints of an airplane would furnish reason for his
presence in the office if Mr. Parsons was still there and asked.

Bob, as Lang left, found Griff suddenly and unaccountably pleasant.

"Funny about that cable," he remarked.

"Sure is," admitted Bob, watchful, quiet, but willing to follow Griff's
unexpected lead.

"Lang says you had your suspicions of me," Griff grinned, quite
pleasantly. Had he, Bob wondered, been "tipped" by Lang to cultivate
friendship? Was there something really underneath the friendship of the
partner's son and Bob's pilot cousin? Was there something else?

"Why, I suppose when we got excited about that broken rudder pull, we
thought of anything and everything," Bob grinned also.

"Well, you thought wrong, friend. Would you try to do any harm to your
buddy, Curtis, if you knew he was to fly a certain crate?"

"No," Bob admitted, honestly and fervently.

"But some other pilot, jealous, maybe--might! Eh?"

Bob had not in any way considered that possible solution. There was
another test pilot, not as popular as his cousin. He gave the most
serious attention, but Griff evidently felt that he had said enough,
adding only: "But I don't mean to accuse anybody. Let's forget it. Come
on, let's forget motors and go up and have a look at them little fleecy
clouds." He caught Bob's arm, after slipping the cylinder head over the
pistons of the model with Bob's help.

"Ever fly a crate?" he asked.

"Not solo!" Bob admitted, "but Lang has let me take the controls six or
seven times when he used to take us up, before we came here to----"

"To what?"

"To learn all there is about building airplanes," Bob continued without
the flicker of an eyelash.

"Hm-m-m! Well, come on, kidlets! I'll take you up in the prettiest
little crate you ever sat in--what's more, I'll give you some experience
so you can fly them crates after you get wise to how they're assembled."

It was evidently a genuinely friendly offer. If it had any hidden
motives, Bob, on that sunny Saturday, with a gentle, warm vacation wind
blowing, with bonny clouds drifting slowly, gave up watching and went in
for air experience.

Al, finally deserted by Sandy, who had errands down town, saw Bob and
Griff warm up the little speed sportster he had been rigging. A little
envious he watched the check-up, the trial spurts of the fast little
engine, the take-off and the soaring of the handsomely designed craft.
Then he went on to visit Jimmy-junior, whose father, Sandy, had given
him a special invitation to spend the afternoon and to stay to dinner
with Jimmy-junior.

Lang, taking the cabin monoplane for a test of his rudder performance,
called Curt to go along; so the trio lost interest in detective work and
concentrated on enjoyment----

Until evening!




                               CHAPTER X
                               A SUMMONS


While Griff, who handled an airplane expertly, was executing dives and
slips, barrel rolls and figure eights, and a loop or so to demonstrate
his skill, Bob, in the rear cockpit seat, wondered whether Griff was
trying to frighten him.

That was not his purpose, Bob decided, and he was more convinced when
Griff, with a grin, turned, after waggling the stick and holding both
hands up beside his head--the signal to "take control."

Bob nodded.

Under Lang's tuition, in several airplanes, during tests, Bob had been
permitted to handle the stick, rudder and throttle. He knew the
elementary movements of straight flying and had some of "the feel of the
air" which comes to any person who has the flying sense: that "feel of
the air" is akin to knowing what the ship is going to do and, of course,
sensing how to meet its various tendencies. When, during a climb, with
too steep an angle, the controls begin to get "loggy" for an example,
the born pilot, or the trained fellow with his air-sense developed,
knows instinctively that the ship is about to stall, and automatically
drops the nose and picks up flying speed.

For awhile Bob, flying straight, or banking and turning, remained near
the small flying field of the plant. He knew the signals with which a
flying instructor guides his pupil, and, handling the dual control
section in his own hands, and with his feet, he made simple maneuvers
under Griff's direction, and seemed to please Griff by the quickness
with which he caught the corrections signaled to him when he
over-banked, or let the ship skid too long without catching the skid.

The trial was over all too soon, and as Griff took over to shoot the
field and set down, the most ticklish part of flying tactics, Bob felt a
trifle sheepish for having suspected him.

Griff was, really, quite a pleasant fellow.

However, Bob began to think. This sudden affable manner must have some
reason behind it. Furthermore, he decided, Griff might be trying to win
his confidence through the hidden flattery of telling Bob what a
"corking" pilot he would make with a little more training. Bob knew that
flying is taught carefully by any self-respecting school, that a
thorough ground-school training and many hours of instructed flight will
be followed by many solo flights, with intermittent check flights under
the instructor's eyes, before a pilot is considered more than a student.
Griff over-flattered.

Bob, as he went home, where Al and Lang had preceded him, his cousin
having stopped in for dinner, decided that he would accept Griff's
offered friendship with a grain of salt.

Al was there, of course, but no confidences were exchanged.

Al had already eaten his dinner, with Jimmy-junior, after a fun-filled
afternoon during which Jimmy had displayed his airplane models, had
supervised many trials while he let his guest wind the sturdy rubber
band motors and set the tiny, practicable controls of the toys.
Furthermore, he had talked about the Sky Squad idea and had begged to be
permitted to join, being air-crazy, as he put it. Al, promising to take
the matter up with his brother and with Curt, had said he would do all
he could to induce them to agree. He could not broach the matter,
however, as Curt, Bob and Lang ate, because Lang was full of the
excitement of receiving a telegram from Bob's and Al's father, the
detective, from a city about fifty miles away, asking Lang to come to
the city for a report and a conference.

Glancing at Bob, both Curt and Al saw that the older member of the
secret membership was disturbed in his mind. Lang would not tell about
Griff, as he visited his uncle over Sunday. That was what Bob was
thinking, as Al and Curt saw. But Curt, looking at his watch, reminded
Lang that he must stop stuffing down the filet of sole, a form of fish
steaks of which he was extremely fond, if he expected to "make" the 'bus
that would pass the house on the way to the city, and the railway
station.

"I'm going to fly!" Lang declared, reaching for more fish.

"Why not take us, then?" demanded Al.

"No. I'm going to borrow Griff's sport model. More speedy and I want to
check before it is turned over to him finally."

"There'd be room for one of us," Bob spoke up.

"No sirree!" and they knew why Lang was so snappish.

Bob pushed back his chair as Al and Curt sprang up. Lang, rising with
his superior, amused grin at their anxiety, waved them back and kissing
his aunt and thanking her for the fish he loved, he departed.

"I'm going!" said Bob, and explained excitedly to his mother that he had
information of importance.

"Lang will tell it," she said. "Explain to him."

Bob's face fell, as did Al's. They were in a box!

They could not explain to their mother that they suspected Lang, at the
very least, of protecting Griff, a friend but not a desirable one.
Whatever their own ideas they were none of them blabbers.

Bob ran out on the porch, leaped down the steps, hopped on his bicycle
and pedaled down the first side street. He was not entirely sure of his
plans, perhaps he half intended to secrete himself in the fuselage of
the 'plane, to go on as an unsuspected passenger; possibly he hoped to
induce Lang to take him by getting there first.

At any rate, as he neared the plant, he was glad he had come.

Griff, at the gate, was in close communication with a mysteriously
furtive stranger!




                               CHAPTER XI
                          A TRAIL AND A FLIGHT


Twisting his handlebars sharply, Bob sent his bicycle into brush at the
end of the aircraft plant grounds where the fence turned; he wanted to
get out of sight.

The pair at the gate were having some sort of argument and probably had
been too excited and absorbed to notice him, Bob decided.

He dropped his wheel and crept back to the corner of the fenced
enclosure to watch.

From that position he could see the man, but only part of Griff's coat
and an arm. The man, as he saw, was vigorously arguing. Griff must have
been either pleading or arguing, Bob guessed, from the man's violent
gestures and appearance of "laying down the law."

Presently a small, flat package came into view.

Bob recalled that he had seen Griff wrapping exactly that sort of parcel
earlier.

The man took it, put it rapidly into his coat pocket, inside. With a
quick look up and down the deserted highway he swung and crossed to a
car parked on the opposite side of the road. Climbing in he speeded up
his engine and drove away at constantly increasing speed.

"So they are dividing the 'spoils'--or Griff was giving him money." Bob,
unable to see Griff, not daring to emerge from his concealment, made the
deduction under his breath. "Well, now shall I follow that man? No,
because his car is too fast. I can't catch him on my wheel."

He decided to wait where he was, to see what would happen. To go in at
once might alarm Griff. He might realize that Bob had been near enough
to see what had occurred; he might suspect. Bob wanted to keep his
presence unknown; Griff had already been warned by Lang; he would jump
to the conclusion that Bob was watching.

Almost at once Bob thanked his good sense for holding him concealed.

Griff, as he watched, ran wildly out into the road and began to wave and
shout after the receding car.

Its driver did not turn around.

Griff, while Bob stared, dashed back into the gateway. For a moment Bob
wondered where the watchman was, then he saw the man, in a small
ice-cream and soda water shack, a little distance down the road opposite
the fenced property. Griff, Bob guessed, had offered to watch the gate
while the man refreshed himself.

Bob hesitated. Where had Griff gone? What was he doing?

The last question was answered by the pop-pop of a motor. Bob knew that
Griff rode a motorcycle. He was getting it started. He meant to pursue
that car for some reason. Something had caused him to want to talk again
with the car driver, Bob mused.

While he watched, keeping all but his head concealed, the motorcycle,
with Griff mounted on it, came sputtering into view.

Never glancing around, opening his throttle, he pelted down the road
after the car.

Bob, without hesitation, rushed his bicycle into the highway and pedaled
after the motorcycle for all he was worth. Griff was too intent on his
purpose to notice, he felt sure.

It would be a losing race, Bob feared, unless Griff overtook that
rapidly receding car very soon. Muscles could not endure against a
machine! Nevertheless Bob rode as fast as his pedals would turn.

As he sent the wheels spinning along it crossed his mind that Lang would
be arriving at the plant almost any moment but he kept on all the same.

"It will take Lang awhile to warm up the engine, and, anyway, if I don't
go with him I know another way to communicate with father," he decided.

The car was almost out of Bob's sight, the motorcycle was rapidly
overtaking it.

At that instant Bob's heart almost stopped beating!

Far ahead, on a cross road, he saw a huge truck come into view. It was
not only between the car and its pursuer; it was also well onto the road
and almost directly in front of the motorcycle.

"Griff!" Bob shouted, without thinking that his voice would never be
heard. He instinctively cried a warning. If the rider had his head low
over his handlebars!----

His coaster brake jammed on, Bob slowed, alighted, his muscles refusing
to function for the instant.

But during that instant Griff evidently saw the huge obstacle and
swerved. In making the wild curve to go around the rear of the truck Bob
saw the youth and cycle go off the road into the ditch.

Evidently unaware that anything had happened the truck driver kept on
down the cross road. Bob, remounting, pedaled for all he was worth
toward the scene of the accident. As he rode swiftly he saw other
figures approaching.

At the point where the motorcycle lay on its side, he was met by Al and
Curt, who had been approaching from the opposite way, up the side road.
"We decided to come and see Lang hop off," Al explained as the trio ran
toward Griff.

He was sitting up, a little shaken, a little dazed, when they
approached. Bob, seeing that he did not appear to be seriously hurt,
caught Curt's arm. "Look here," he said quickly, "I want to go with
Lang. Don't say I was following--you know--keep it quiet. I must get to
see father and tell him----"

"All right. Don't waste any time. Get out of sight. I'll tell Al."

Bob hurried off, as though he was in search of aid, and he felt, as he
pedaled back toward the field, that Griff probably had been too much
shaken to notice that Bob had come from the direction he had been
riding, or deduce that Bob had followed him.

The watchman, and several others from the soda stand came running down
the road. They called out as he approached and with a brief explanation
that there had been a "spill" but that he thought it was not serious,
Bob rode on.

He found Lang riding toward the plant, and swung his bicycle in at the
gate and set it against the fence.

"What's the trouble, up there?"

"Griff took a spill going around the back of a truck that came out of
the side road. I think he's all right." Bob called out his answer to
Lang's shouted inquiry and saw his cousin ride on to investigate.

Bob, with some idea in his mind that he might crawl into the fuselage of
the small speed 'plane, and, thus stowed away, be carried to the city
from which his father had telegraphed, changed his mind. The close,
smothery fuselage, subjected to the most violent rolling and heaving of
the airplane's progress, would probably make him ill. He preferred to
stay outside, to see what happened, and to compel Langley to take him as
a passenger.

Watching from the gateway he saw that Griff had been lifted to his feet
and had apparently found himself only rather badly shaken. This was
Bob's decision because he saw a passing car driver help the shaken youth
into his car, tumble the motorcycle out of the grass and turn it over to
the plant watchman to be trundled back, and drive off to take Griff
home, it seemed.

Bob met Lang beside the propeller of the little speed craft.

"Get the ignition key from Griff?" he asked.

"I did."

"Climb in. I'll give the prop a twist for you."

Langley got himself set.

"Gas on?" called Bob.

"Gas on."

"Switch off?"

"Switch off!"

Bob gave the propeller a couple of revolutions.

"Contact!" he cried, leaping aside to avoid the flailing, knife-like
edges of the blades. The engine caught on the touch of spark to
compressed gas mixture.

While Langley opened the throttle and warmed up his engine, Bob
unconcernedly began to clamber into the after cockpit seat.

"You're not going!"

"Oh, yes, I am."

"Get out of there!"

"Listen, Lang," Bob leaned close to Lang's ear to carry his message
above the noise of the radial engine, "which suits you best? To have me
with you, to tell dad what I know before your face--or to have me
telegraph him while you're on your way, and let you explain to him what
I have to tell?"

Lang, at first furious, presently saw the logic of Bob's position.

"Oh--all right!" he grunted and "gave her the gun" in somewhat vicious
spurts.

Bob, fitting on the "crash helmet" kept in the 'plane by Griff for him
that afternoon, and the leather jacket and gloves, smiled.

He was progressing as a Master Sleuth, doing his share creditably for
the Sky Squad.

As soon as the engine was sufficiently warm and methodical Lang had
checked all his instrument readings, the trim little ship taxied down
the smooth field to head into the wind which Bob saw, from the
"windsock" blowing out from its mast on the office building, was from
the south, a nice, light, Summer evening breeze.

The watchman, coming in, put aside the slightly damaged motorcycle and
strolled across to the hangars, into one of which he stepped to throw a
switch, lighting the flood light by which they could see to take off. He
did not question Lang's right to use the craft because Lang must have
gotten its ignition key from Griff, its owner.

As they took the runway, and increased speed to the throaty roar of the
engine, Bob felt that sense of the ship getting "light" which indicates
to the pilot that she is ready to take the air. He saw the elevators
tip, glancing around swiftly to check the safety of the way ahead, and
then saw the lighted earth dropping, contracting into a spot of vivid
light against a field otherwise dark; then the watchman shut out the
floods to avoid confusing them in the air, and the ship climbed into
dark night.

They had climbed several thousand feet and were headed into the north,
so that Lang could "pick up" the lights of the airway along which his
night flying would be easiest, when Bob saw him double unexpectedly.

For an instant the craft's nose went almost straight down and Bob was
glad he had strapped himself in; then Lang evidently caught control, and
the stick, thrust forward as he doubled, with some unexpected convulsion
or "stitch," was pulled back and brought the ship out of the dive
gradually.

"What happened?" Bob screamed above the engine noise, the song of wind
through wires caused by their dive.

"Cramp!" called Lang, cutting the gun as he held a glide for a moment,
turning a white face toward Bob. "Listen. Bob--oh!----"

He bent again. "The fish--too much fish--" Bob guessed, and had he known
that Lang's delay in reaching the field had been due to further
refreshments, he would have said, "Fish--and ice-cream!"

At least that was a far more reassuring thought than Bob's first idea,
that some one had tampered with some control of this craft.

"Oh--" Evidently Lang was very ill.

Suddenly, as he saw his companion in the forward seat double, Bob felt
the stick waggle against his leg.

In an interval between his spasms of violent pain, Lang held up his two
hands alongside his helmet.

It was a signal for Bob to take control.

"All right!" he called, and, with a steady hand, he clutched the stick
of the controls in his cockpit, set his feet against the rudder bars,
and eased his throttle open to regain speed.

He was not in the least nervous or flurried. He pitied Lang's cramped
stomach and evident suffering, but did not permit it to influence his
steady nerve. He had been given enough lessons to know how to hold the
craft in level flight. While night flying was not as safe and easy as
daytime work, he knew that if he followed the ribbon of lighted highway
that ran toward the beacons of the nearest airway, he could always "set
down" on the asphalt, if worst came to worst, and if he did smash the
trucks, the landing gear, he did not think he would do any more serious
damage.

"Had I better set down?" he shouted, gliding for speed as he cut out the
engine roar. Lang shook his head and gestured forward. Evidently he was
not afraid of any immediate physical collapse and preferred to go on
flying to see if he would recover. Bob held on.

He picked up the beacon and, watching Lang's gestures, swung in a long,
banked curve, to head across the wind down the unconfined airway, whose
second beacon he could see, far away.

By habit looking around to be sure no other ship was close as he turned,
Bob, startled, saw the flying lights of another craft pursuing.

It must be pursuit! It came from the direction they had come. It turned
as they turned, only in a more sharpened bank, so as to cut off part of
the distance, it seemed to Bob, to close the gap between them.

"Lang!" he shouted, and waggled the stick.

Lang looked around.

Bob's arm pointed backward and upward.

Lang, leaning out of the cockpit, to see around the wing-tip, stared.

"The cabin 'plane!" he cried. "I know it. Golden Dart."

"After us?"

"I don't know!"

But as Bob opened the throttle to regain flying speed without having to
dip down too low, there came from the other ship a red flare.

It was, as Bob realized, a signal--not of danger but of command.

"Land!" it commanded.

Bob looked at Lang.

Lang considered. As he hesitated Bob guessed his thoughts. Some one from
the small field, some member of the plant staff, probably Mr. Parsons,
finding the 'plane belonging to Griff gone, and hearing from the
watchman who had taken it, had taken off in the cabin monoplane to stop
what he probably considered a prank of Lang and Bob--some night-flying
lark.

What would Lang say? Set down? Or--go on?

They could outfly that cabin ship in the speedy, easily maneuvered sport
craft--or, they could, with Lang at the controls. But Lang was badly
upset in his stomach. What would he decide? Bob mechanically looked
around for the best spot to set down.

When he looked up again his heart leaped with exultation.

Lang's arm pointed straight ahead!

"Go on!" he gestured.

Bob opened the throttle joyously. Here was adventure, pursuit, thrill
enough to suit anyone!




                              CHAPTER XII
                               THE CHASE


Rapidly Bob considered the situation.

The speed craft he and Lang occupied had much the best of it on a
straight flight, but, against that, he had to set his inexpert handling.
The smaller craft could out-climb, out-maneuver the cabin ship but he
had no experience in stunting, especially dangerous at night.

Therefore Lang's decision was the safest one.

To try to make a landing, Lang evidently concluded, was not wise. He
felt that he could take over the controls before that need arose, Bob
guessed.

A new complication came, however.

If the cabin ship had the disadvantage of being slower, she had gained
an offsetting advantage before they saw her. She was much higher in the
air than their craft; she could dive, if her pilot chose, and thus close
the distance between them--maybe come down "on their tail," or ride them
to earth, if her pilot proved to be determined to force them to land.

Accordingly Bob opened the throttle wider, and slightly elevated the
nose to climb.

Lang, peering upward and to the rear, made a violent, vigorous gesture.

Bob, reading it, understood.

He did not question. Lang called for a sideslip!

Instantly Bob manipulated ailerons and rudder correctly and felt the
wind on the cheek toward the lower side of their bank, telling him they
were slipping.

Then, applying rudder and other controls to check the slip, dropping the
nose again to pick up flying speed quickly, he saw why the maneuver had
been executed. The cabin airplane had begun to dive down from above
them. Lang, having seen it, anticipated. He had not wanted to wrest away
control--too dangerous. He had risked the signal, and Bob had executed
his order accurately.

He was glad, all the same, when Lang shook the stick, tapped on his own
helmet to sign that he wanted the controls.

Bob relinquished them thankfully enough. At night, in strange
surroundings, in an airplane he had only handled a little, he was not
foolish enough to wish to risk neck and limb--far less Lang's than his
own!--by trying to outfly a pilot who evidently meant to be vicious, to
resort to war tactics if they did not obey his signals.

Lang, somewhat recovered, took over and Bob, delighted, watched his
expert manipulation of the splendid little ship. She answered his every
command. He barrel-rolled out of the way of any immediate danger, thus
leaving the cabin craft well to one side. He started up a loop after a
swift dive, but at its top he executed half of a barrel-roll, and since
the top of the loop had the nose in the direction opposite their course,
the half-roll put the craft on its level, upright course, but going
directly away from the former one.

The cabin ship could not be stunted that way, or else its pilot against
his will was compelled to recognize superior tactics.

At any rate, as Lang swung around in a wide circle, slowly climbing at
the same time, the other craft seemed to be heading uncertainly back.

It came around, however, as soon as Langley straightened out on the
former course along the airway; but they rapidly outflew it and when
they landed at an airport in the distant city suburbs, the cabin ship
was nowhere in sight.

It was nearly eleven o'clock at night when Bob and Langley were ushered
up the hotel elevator and along a corridor and into Mr. Wright's rooms.

The detective, who had been apprised, long distance, by his wife, that
his nephew was flying to keep the appointment, was waiting.

Hardly had his surprise at Bob's presence been expressed and a late
supper for the air-hungered pair been ordered than another visitor was
announced.

"So this is where you were bound for!"

To Bob's amazement, Barney spoke.

"Why didn't you leave word that you were coming here?" he said, rather
sharply. "We could all have come together."

"We didn't know you were on your way here," said Langley.

"We thought you were chasing us," Bob added.

"So I was. The watchman said you hopped but he didn't say where to. I
was coming over to confer with Mr. Wright, but I thought Lang and you,
Bob, were joy-riding. So I signaled you to land and when you didn't I
decided to scare you into setting down--but it failed."

He chuckled.

"I ought to know better than to think I could outfly Lang," he said.
"Well--if you've come with information, it's all right. We can have a
conference, all together."

They did so, over the dinner. Lang listened to Bob's recital of the
latest developments about Griff, with growing anger, until he saw
Barney's face.

"Good boy, Bob," commented Barney. "I've sort of had a notion in my head
for some time about----"

"Griff?"

"Yes. I've thought he was the one who's crossed the wires on us and
short-circuited the whole plant. So he divided with somebody, did he?
Well--he must have gotten it from somebody higher. Have you thought
about?----"

"His father?" broke in Bob. "Yes--we have!"




                              CHAPTER XIII
                         THE DETECTIVE'S THEORY


More startling than Bob's fresh information was the revelation given by
Barney, the information which had brought him, flying, to consult the
detective he had engaged to solve the puzzling case.

All that Bob had to tell was the suspicious act of the youth, Griff.

Barney, because it was so late, gave only a hint; but what he said
caused a great deal of sleeplessness on Bob's part, at least.

"We got the wrecked airplane up," Barney told them all, that night.
"I've had it hauled in and dismantled."

He paused to give his next words more emphasis.

"There wasn't one thing wrong with that crate!"

When, during their Sunday morning conference, he amplified his
statements, the mystery deepened.

Dismantled, thoroughly examined, by Barney, in person--he did not trust
any subordinate in so important a matter--the airplane revealed nothing
wrong, either with its engine, with its wings, or with its controls!

"But it fell," commented the detective. "What, do you imagine, caused
the crash?"

"I give it up." Barney was unable to make a theory. "I hired you to do
the doping out of that! I give you the facts. You do the rest."

"Bob," his father turned to the youth, "have you jotted down all the
suspicious things you mentioned, as I asked you to do?"

Bob nodded and handed over a paper.

After consulting it and comparing it with a sheet on which he had
written, Mr. Wright looked up.

"This is what we know," he began. "For several months, according to
Barney's original explanation, when he gave me the case, airplane parts
had been missed. Not very many, but some. We have to decide how they are
taken, and then find out who does it and what happens to them, how they
are disposed of."

"How about the man who gives out the instruments and such?" asked
Langley quickly. Bob thought he said it to forestall comment about
Griff, "or the mechanics whom Al had been told by his rigger boss were
possible culprits?"

"We haven't been able to watch everybody," Bob said.

"That point is not important," Mr. Wright declared. "It is the beginning
of what we know, and can wait. Our second bit of knowledge--and more
important this is, too--is that for several months before the seemingly
fatal crash, accidents had occurred to every airplane that was sent out
of the plant. Buyers complained by letter, and only by good luck was it
possible to avert several tragedies."

"I didn't know it had been as bad as that," Bob commented.

"It had," Barney nodded. "We wanted you three boys to start in with open
minds. Remember? We didn't tell you details; but now it's gone too far
for taking things easy. We've got to get to work."

"Right," agreed the detective. "The third point we know is that Mr.
Tredway was very anxious to hold up the good name of his corporation,
and that he decided to take this last ship to its owner in person, after
Lang, here, gave it--" he paused, noticing Bob's expression.

"I know what's on your mind," Langley said, turning to his younger
cousin. "I was the one who tested and checked that Silver Flash. I said
she was O.K. before the take-off. But," his manner was defensive, "if
you think----"

"I don't think," Bob asserted. "For a minute I did--but Mr.--but Barney
says not a thing was wrong about the Silver Flash. So, of course,
there's nothing to think."

"Besides," said Barney, "we none of us knew it would be the Silver
Flash. The buyer couldn't make up his mind, till almost the last minute,
about that pair of twins. One time he'd come and say he liked the
silver, then he wanted the copper-gold finish. Both crates were
identical except for that. I thought, myself, he was going to
take--well, we all thought the last time he came he wanted the gold one.
But I guess he telegraphed."

"Well, then, that explains one thing," said Bob. "If everybody thought
he wanted the Golden Dart, that's why the rudder rope was frayed off in
that ship." Barney, who had been told everything, nodded.

"Yes," he admitted, "but that don't explain why the other ship--sound
and perfect--crashed. Unless----"

"Unless--what?" Bob, Lang and the detective were interested, but Bob
voiced the question.

"Unless Mr. Tredway did it on purpose--crashed!"

"Why should he?"

To Mr. Wright's quiet inquiry Barney answered readily enough.

"I run the plant," he said. "The deep part of the money end, and all
that is none of my business. But I happen to know there's some trouble
about money, or losses, or something like that."

"You think--" Mr. Wright bent forward, "--Tredway, because he was in
some financial difficulty, or deeper trouble, might have done away with
himself?"

"Well," defensively Barney replied, "how else do you account for a
diving ship, placed so careful, on the lakeside, close to shore, and
only damaged as little as possible, and then not from anything being
wrong in her?"

Bob saw that his father was very thoughtful.

"Do you think he ran off and hid, afterward?" he demanded.

"They didn't find hide nor hair of him, did they? Dredging, or searching
didn't locate anything!"

"That's so!"

"However," the detective objected, "that doesn't explain about the
frayed cable, or the other things done to airplanes to damage the
reputation of the corporation; that is my theory about the motive."

"No," Barney admitted. "If you've got a theory about the motive for
damage to crates, maybe you've got one about the whole affair."

"I have."

"What is it, Father?" Bob was eager to hear.

"There are three crimes to investigate," Mr. Wright said slowly. "The
accidents, the thefts, and the----"

"Do you still think Mr. Tredway's disappearance was due to a crime?"

"Yes, Lang, I do."

"What sort of crime? Nothing is wrong with the ship he used, Barney
says," objected Bob.

"A very strange one," his father replied. "Remember--there was a brown
airplane hidden in a field. It was gone--before the accident. My theory
is that either some one he feared, or some one who hated him, took off
in that brown airplane, overtook or waited for Mr. Tredway--and----"

"Rode him down!" gasped Barney. "I'd thought of that!"

"Yes," agreed the detective, "let's drop all worry about the less
important thefts, the deliberate damage to the airplanes--and look for
the man who flew that brown airplane!"

"Will we?"

Bob asked it as a question, then he repeated it as an exclamation.

"Will we!"




                              CHAPTER XIV
                         THE SKY SQUAD DISOBEYS


Both Curt and Al listened eagerly while Bob related the details of the
Sunday conference with the detective.

He gave them the information imparted by Barney.

"Not a thing wrong with the Silver Flash?" repeated Al. "Then that brown
crate must have driven it down--but why?"

"Maybe some revengeful pilot Mr. Tredway had discharged," suggested
Curt. "At any rate there must have been some motive to make a man do
anything as terrible as that. But how are we going to locate the brown
ship?"

"I still have that message we discovered on the seat, and then picked up
in the dewy grass." Al produced it, dry but smudged and crumpled, from
his pocket card and identification case. "We might compare the writing
with the--well, say with the books in the aircraft plant, and with
everybody's writing."

"Lang didn't get any information when we made inquiries about the brown
craft at the nearest airport, did he?" Lang, who was quite affable and
good-humored, with Griff and his actions forgotten in the new search,
answered Curt.

"No, nothing more than you did. They'd never heard of the ship I
described."

"_You_ have got me more puzzled than this whole mystery has," Al said,
grinning. "Lang, the way Bob tells it, you must have been next door to
ordering the undertaker, and then you were flying, stunting, as if you'd
never eaten fish and ice-cream."

"That's psychologically explainable," Lang liked to use long words, to
indicate his superiority. "Under the stimulus of----"

"Never mind!" Al threw up his hands as if to ward off a flow of words
too long for his youthful understanding.

"It's too easy to explain," Bob said. "Father said Lang got so excited
that he forgot to think about himself, and 'Nature took its course' when
he stopped worrying about his fears."

"That was it," agreed Lang. "I accepted the idea, from somewhere, that
ice-cream and fish made poison, and while I was flying, when a little
gas began to bother me I got scared, and the scare did the rest. Uncle
said that half our pains are due to believing what other folks tell us
can happen; the rest is from being afraid it is happening to us!"

"That clears it up." Al became very sober. "I wish the disappearance of
Mr. Tredway was as easy to settle."

"Well, we'll have to find that mysterious brown 'plane, or get hold of
somebody who saw it flying, to tell us which way it went." Lang rose,
stretched, yawning, and sauntered off toward his wheel; the other three,
sitting on the cottage porch before supper, for which Lang would not
stay, looked after him in silence.

"Do you know what I think?" Curt broke the thoughtful pause. "I don't
mean to criticise, and I don't want you fellows to get angry, but I have
a feeling that Uncle Fred is wrong to have us drop all our suspicions
and try to find a crate that could be five hundred miles away, in any
direction. My theory is that if we locate the airplane it will be by
'luck' and I don't believe in 'luck' because if you think 'luck' is
going to help, you don't have to do anything yourself, and if you
believe it is going to hinder, there's no use in doing anything. So," he
grinned, "I believe that everything comes out right only when we do
everything we can to make it so--and as long as there isn't any way to
start hunting that brown crate, let's----"

"Disobey?" asked Bob, rather surprised.

"I guess it would amount to that--and in another way it wouldn't!"

"How could it if it didn't and why wouldn't it if it did?"

The others laughed at Al's twisted inquiry.

"Uncle Fred didn't give you orders to 'lay off' watching, did he, Bob?"
and as Bob shook his head, "He only meant for us to concentrate on
seeing if we could pick up a clue to the mysterious 'plane. Well, I feel
that by finding out what Griff is doing, and why his father is so
fidgety and furtive, and the rest of the puzzles here, we may be led to
that 'plane, or get a clue to it or to its pilot."

"I don't see any disobedience in that."

"Well," Curt answered Bob, "the way I look at it, if Uncle Fred took us
into the case he expected us to obey the 'spirit' of the orders he gave,
and he did say to forget the smaller things here and work on locating
the 'plane."

"I see," agreed Bob. "It's a pretty deep--what Lang would call, ethical
problem. Father meant to leave Griff alone, unless he did something
actually incriminating, and to put all our effort on the other thing.
Let's see your paper, Al." He held out his hand for the brief note Al
had preserved.

Study it as they would, they got nothing helpful from the grass-stained
paper with the smudged writing.

"Let's think who we've seen use an indelible pencil," hinted Al.
"Remember, the morning we found this, we decided, in a joke, that there
were too many indelible pencils to try to trace the writer because he
used one; but how many people close to this mystery have you seen using
one?"

"The clerk in the supply room!" gasped Curt.

"Are you sure?"

"Yes, Bob--because he takes a copy of every order he writes and of every
requisition, on an old-fashioned letter press, the same way they put
their copying ribbon letters in between a damp cloth and a soft, thin
sheet of the big book, put it all in the press and make the copying
ribbon print the letter into the book instead of using carbon paper!"

"Then we have a clue! How does the clerk's writing compare with this?"

"Let's see!"

Each of the three having spoken in turn, by common consent they agreed
to Al's impulsive suggestion. They were hardly able to wait for their
supper; however, they put it away with speed if not with the best of
table manners and secured their bicycles.

It took them only a short time to reach the aircraft plant.

The watchman accepted their explanation that they were passing and
wanted to borrow several books from Mr. Tredway's reference library, in
the offices.

Bob, accordingly, went to the offices, while Curt and Al strolled, with
apparent aimlessness, across the inner quadrangle.

"There's a light in one window--no, in two windows--already!" Al
mentioned. "I wonder who's here, at night again." Almost at once he
suggested that they go and see.

Curt, himself fired by the curiosity of his companion, hurried after Al.

They saw Bob, who had lighted the outer office electric bulbs, choosing
several volumes from a shelf, to carry out in truth their explanation to
the watchman.

"Now--who's here?" Bob said, joining the others at the door as he put
out the light.

"Can't be Barney--unless he came back--no, the cabin 'plane isn't here,"
Al argued. "Anyway, Barney stayed over to transact some business, you
said, Bob. Must be either----"

"Griff, or Griff and his father--or Mr. Parsons and somebody else," Curt
said breathlessly, excited. "There were two separate offices lighted,
and you can see the door glass shining."

"The doors are shut, though," Al spoke, disappointedly.

"Yes," continued Curt, "but one of us can hide in the alcove where the
water cooler and door to the washroom are located. If anybody comes, it
would be easy to dodge on into the washroom and no one would ask
questions about that."

"Then you're elected!" Bob said. "I want to go with Al, because I think
I know where to find the latest letter-book."

With the reference volumes tucked under his arm he led Al down the dim
corridor, while Curt secured a good place in the niche by the water
cooler to watch from.

As the two brothers went down the steps, at the rear, toward the supply
room, to be sure that no one was there and likely to come up and catch
them, Al's grip on Bob's arm tightened convulsively.

Some one was coming down the steps behind them.

With lips close to Al's ear, Bob whispered:

"Tiptoe! Come on!"

He led Al down to the lowest steps, and there, just beside the door to
the supply room the brothers flattened themselves against the wall.

They held their breath. They made themselves as small as they could. A
quick tread came on down the steps, there was the pause of a body
close--almost touching them. Breathing, sharp, short, quick, carried to
their ears; but they kept mouse-still. The door opened.

A light flared up as Bob dragged Al back out of range. But as they
turned and stared down, hearts still pounding from the excitement of the
narrow escape, both brothers gasped.

In the light below, stood--a bearded stranger!




                               CHAPTER XV
                             A TRIPLE TRAIL


Pulling Al further back out of the light, around the little dark jog
beside the door jamb of the supply room, Bob put his lips close to his
brother's ear.

"Watch!" he whispered, hardly loud enough for Al to hear.

With a little squeeze to reassure his brother, Bob let go of Al's arm
and tiptoed back up the stairway, carefully clinging to the side wall
and hoping that this precaution would enable him to get away without
causing the steps to creak.

He was successful. Al, noting that the man inside the room seemed to be
doing nothing more than standing there considering the layout of the
place, guessed that Bob wanted to consult with Curt, watching upstairs.
Al felt important: he was in the very heart of mystery, and much
depended on him. Therefore he watched with every faculty alert as the
man turned his head this way and that, apparently inspecting the stock
of wing and fuselage cloth, the boxed instruments, the cases of "dope"
for varnishing bodies and wings, the many other visible objects held in
reserve.

Bob, slipping along the hallway at the top of the steps, noticed that
both offices were lighted still, that both doors were closed, and as far
as he could see, nothing had changed up above.

Curt was still watching. He was practically invisible in his nook by the
water cooler. Bob, with a small word under his breath, reassured his
comrade who came out of hiding as soon as he knew that the footsteps he
heard approaching were Bob's.

"Where did the stranger come from?" asked Bob softly.

"Stranger?" Curt's voice betrayed amazement.

"The man who came down to the supply room!" Bob was also surprised.

"Was he a stranger?" Curt asked. "I thought it was Mr. Parsons. He came
out of that dark directors' room, beyond me."

"Oh!" Bob clutched Curt's arm in a tight grip. "Have you used your eyes,
Curt, in daylight? If you have, you recall that there is a fire escape
running up the side of the building--and the landing is by that
directors' meeting room window."

"Is that so? Then, if that window is open----"

The opening of one of the lighted offices startled them, ended the
consultation. Both comrades, tense, drew close against the wall behind
the water cooler. If anybody was thirsty!----

The lighted square of that door went black. Someone had put out the dome
light. Footsteps went carelessly along the corridor from the hiding
youths, toward the front stairway.

"I must follow--whoever it is!" whispered Bob. "Curt, watch here. Al
will watch that other man. It's----"

"A triple trail!" gasped Curt. "Go on, Bob. Be careful."

Bob agreed and tiptoed along to the stairway. By the time he got there
he had no need for special caution, the lower door was closing.

Bob ran lightly down the stairs, crossed the entry below, cautiously
peered into the yard, lighter just there by the arc over the office
building doorway, and nodded to himself.

Griff was passing around the side of the building!

Cautiously Bob trailed him, allowing the partner's son to get out of
sight beyond the turn before he left the doorway.

Where was Griff bound? The main gates were across the yard and, as Bob
knew, they were locked while the night man made his rounds of inspection
among hangars and plant structures.

While Al watched his man in the supply room, while Curt hid, watching
the lighted office door, Bob wondered what Griff was about. The young
man did not go anywhere near or bend his steps in the direction of the
main entrance but turned, with Bob carefully watching as he clung close
in the shadow of the office structure, and went on around the building
toward the private exit used by the officials. Being the son of Mr.
Tredway's partner, Griff had a key; but Bob could see, as he peered
around the building, that the gate stood slightly ajar already.

"Will he go on home?" Bob wondered. "Had I better go back to Al?"

His thought was answered by Griff's actions. He paused at the gate,
seeming to inspect it. He was surprised to find it ajar, Bob decided. He
held his place close to the office shadow and watched, as Griff looked
around, inside and outside the fence.

Then, as though discovering something, Griff ran out of sight, leaving
the gate as he had found it.

Instantly Bob ran across the small open space to the gate. There, in
sudden caution, he cuddled his body close to the fence; it had just
crossed his mind that Griff might have gone outside in a pretended hurry
to draw out any pursuer; he might be hiding, watching!

He was not, however.

The sputter and roar of a motor startled Bob.

"That's queer," Bob mused, while he projected his head through the
gateway. Almost in the same instant that he saw Griff starting up a
motorcycle, Bob saw Griff shut off the motor and trundle the machine
away.

"His own motorcycle is broken, since Saturday's accident," Bob
reflected. "Now he must have brought another one. He meant to ride off
in a hurry," he deduced, "but he decided the noise would startle and
warn people, so he's going further away before he starts up."

Instantly his own action was decided upon. He streaked back across the
yard, around the hangars, to get his own bicycle. Against a speedy motor
it would not keep Griff in sight, but it would enable Bob to get over
the ground faster, and, if Griff did not go home, Bob meant to pursue
him, making careful inquiries as he pedaled. There was only the
crossroad for him to take, and Bob could see it from the highway.

In a very short time, and without having been seen by the watchman, Bob
was out on the road. The distant sputter of the motorcycle engine and a
speeding form passing the junction of the crossroads gave Bob all the
information he needed. Without wasting energy in an effort to keep the
flying cycle in sight, he pedaled after it.

The sudden sharp noise evidently startled others besides Bob.

Al, watching, saw the man who was evidently making some notes in the
supply room, suddenly dash to the switch. Out went the light.

Al heard the scrape and rumble of a window being unfastened and thrown
up. The man was listening, he judged.

Curt, by the water cooler, heard nothing but the faint sounds of the
motor; at first he thought they were shots. When he saw the office light
go out suddenly, immediately afterward, he thought someone in there had
shot at some one else; but the door was flung open and he heard hurried
feet pounding along the hall and almost stumbling down the front steps,
careless of how much noise they made.

Curt could not go to explain to Al. He must see who that was going out
of the quickly darkened office so swiftly.

Al needed no one to warn him. He crouched, tense and listening intently,
outside the supply room door for a full minute. Absolute, torturing
silence began to twitch his nerves. Nameless fears and countless
uncertainties filled his mind. Was the man stalking him? Was he there at
all? Had he ever been there? Was he human--or----?

Al heard a queer sound; at once he identified it. The window was being
quietly pulled down.

Again he listened, watched, waited.

Curt, slipping down the banisters in the good, old-fashioned, speedy
boys' way, landed quietly at the foot of the stairs soon after the front
doors of the office building closed.

But by that time whoever had emerged was far across the quadrangle and
it was too dark to recognize him. There came the flare of the headlights
of an automobile.

From its position on the grounds and from the style of its lamps, Curt
guessed it was the runabout used by Mr. Parsons, Tredway's remaining
partner. What was he doing here? Where was he going? Curt, in the office
doorway, not daring to emerge because of the beams of light that might
swing around the yard at any moment, heard the voice of Parsons hailing
the watchman, questioning him. The other replied in a way to show he had
not heard any noises, could not account for them.

Curt, as the car got under way and the main gate was flung wide to
permit it to depart, raced around the office building "ell" and across
to his bicycle. He knew he could not pursue, but the wheel would give an
excuse for emerging from that gate at once.

"Wait!" he called to the watchman, pedaling swiftly across to him. "I
guess he forgot I was here," pretending that Mr. Parsons sponsored his
presence there so late at night. The watchman said nothing but held the
gates open until Curt pedaled through and took his way after the car,
not to keep it in sight but to see if it went to its owner's home.

Al, ignorant that he was the only remaining member of the Sky Squad,
watched tensely and listened alertly beside the supply room door. He
heard nothing. Cautiously he protruded his head around the door jamb.

The room was silent, evidently the man was hiding or--"gone!"

"But how--where--could he go?" Al answered his own questions at once,
for the window, made of tiny panes of thick glass between heavy bars,
locked always from inside, impossible to open from outside, was not
tightly shut.

For once in his life Al paused to think before he acted.

That window was not tightly shut. He had heard it opened, and--closed.
But if the man had closed it from within the room he would have pulled
it down tightly. He had not done so. He had left it partly open--why? To
provide a way to come back, Al decided.

Almost at the same instant it flashed into his head that if he were to
be caught in that room, with its door unfastened, he would be accused by
any of the plant members, the watchman or those he thought were still in
the upstairs offices, of stealing whatever might be missing.

He had a plan, at once!

He tiptoed back to the steps, listening. No sound came to him. Softly he
went into the open doorway, made sure the window was not tightly shut,
by inspecting the lighter space beneath it, then very quietly let the
door go shut, allowing its spring lock to snap. He could open it from
inside if he had to escape. No one without a key could open it from the
hallway.

Then he ran close to the window, peered out, listened with an ear to the
crack beneath the lower panes.

Nothing was stirring. But from the window he could see the gate, and the
light was sufficient to show him a man's form arriving there.

Evidently the form stopped from surprise or caution, then it went
swiftly out. Al, forgetting fear, flung the window slightly upward,
edged out, dropped to the ground, reached up and almost closed the
window, then fully drew it down with a little slam, and raced to the
gate. There he paused, peering out carefully.

Down the narrow lane he saw a man's form trudging rapidly.

The third trail was opened!

After the man, at a distance, trudged Al!




                              CHAPTER XVI
                             THE "WINDSOCK"


For Al the trail ended abruptly after a walk of a mile. The stranger,
whose face, with its heavy beard, Al could not dare get close enough to
identify--even if he knew it!--hailed a passing automobile, asked for a
"lift" and was taken in. That concluded Al's chances of following
because no other car came along. Dejectedly he returned to the aircraft
plant to discover that some one, perhaps the watchman, had closed the
gate. There was nothing left for him to do but to go to the main gate,
call the attendant and get his bicycle. His friends were gone, the man
assured him, and Al had no excuse to stay there.

Dejectedly, feeling that he had been close to a clue and that it had
slipped through his hands by his "bad break," Al rode home.

Curt's trail took him, eventually, to the Parsons cottage. Seeing the
car drawn up before the garage, Curt decided that he had no need to
watch the car being put into the garage; evidently its driver had gone
into his home for a moment first. Curt rode away. Had he waited his
trail would have led further; but he did not guess that!

Bob had better fortune.

He saved his strength as he pedaled along, well ahead of his two less
fortunate trailmates, and when he came to a cross street of the suburbs
where a policeman was directing traffic Bob drew up beside the officer.

"Hello, Bob!" the policeman hailed. "Out sort of late, hey?"

"Yes, Mr. O'Brien. I stayed at the plant--I'm learning how they put
airplanes together at the Tredway plant. I wanted to ask if you noticed
a motorcycle, not long ago--maybe fifteen minutes--a friend----"

"Yes," the officer, starting the cars down the street by a wave of his
hand, did not wait for an explanation of Bob's reason for the question,
"Griff Parsons rode by."

"That's who I mean. Did he turn off, here, to go home?"

Bob knew that Griff's house was several blocks over, on an up-and-down
street that was "one way" for traffic. If Griff had turned here Bob's
quest, he knew, was over; if he did not, Griff would be gone much
further, because if he did not turn here, and thus enter his own home
street in the right direction he surely would not go on and approach it
in the wrong way, against the traffic rules.

"He rode on by, just waved to me," O'Brien said, and turned to signal a
warning to a car that was trying to slip past the stoplights.

Thanking him Bob rode on. Griff must be going somewhere!

The highway had no turns, except the suburb's cross streets. It was
possible that Griff might have turned into one of them, perhaps to
return a hired motorcycle to its garage; nevertheless, so strange had
been the action of the youth that Bob decided to ride on, at least to
the last police officer along the main traffic road, to see if he could
learn whether the trail continued or not.

The traffic officer, used to seeing this rider, greeted Bob and told him
that several motorcycles had passed him. Bob, riding to the curb to
rest, was puzzled. Had one of those been the motorcycle he had followed?

A thought caused him to ride on.

Griff, Bob knew, from his own inquiries, "hung out" with quite a rough
crowd of youths; they had very little reputation in the suburb, and one
of their haunts, near Rocky Lake, came to Bob's mind. Griff, riding his
motorcycle, might have gone on to the inn or roadhouse or "speakeasy" or
whatever it was, near the picnic grounds at Rocky Lake.

Tired, but determined, Bob went on.

Some time later he approached the gayly lighted roadhouse.

He smiled to himself as he observed the name of the place.

"The Windsock!" it was called.

On roadside signs, down the road in both directions, were admonitions to
automobilists to "set down at The Windsock," "Don't fly past The
Windsock," and such tempting notices.

A windsock, Bob knew, was the cornucopia of doped cloth, closed at one
end and held open at the other by a metal ring, which was fastened in a
prominent, high position at every flying field and airport, to be filled
by the draft of a breeze and thus, by its position, to indicate to
flying craft which direction to "head in" or to "take off." Since an
airplane is much easier to get off the ground, and back to earth, headed
into the wind, the "windsock" was a most important adjunct to every
field; and Bob knew that the name, and the symbol, a real windsock on
top of the inn, had been chosen by its owner because he had been an
ex-pilot who put his money into the hotel venture and tried to attract
picnickers, automobile parties and other patrons of a less savory nature
by the novel idea of having his dining alcoves built to resemble the
cozy little cabins of airplanes and had his meals served by girls clad
in suits and helmets resembling those worn by pilots. Also, he had let
it be rumored around town that he chose the flying symbol and the
aviation idea because, in his inn, "the sky is the limit!"

Bob, approaching, was surprised to see the very motorcycle--he was sure
of that!--he had followed, leaned against a post in the parking yard,
and he felt certain that his long ride had not been wasted.

Where was Griff? Bob wondered. He hoped there would be some way for him
to discover the whereabouts of the youth.

Not wishing to walk into the place for fear he might disclose his
presence to Griff, Bob skirted the building, unobserved.

From an open window at the side came voices in angry altercation.

Bob did not need to get within sight of the occupants: he recognized
Griff's loud, sharp, furious tones. What was he saying?

"----all I could scrape together--I _did_ put it in that package, I keep
telling you----"

"Bologna! Rats! It was wads of paper!"

"It was money! I want my receipt! If--if you don't!----"

"If _you_ don't, you better say. If you don't come through--by this time
tomorrow night--I'll ask your old man for it!"

There was silence.

Bob did not dare creep any closer. They might look out of the window.
Some payment had been made, by Griff's claim. By the denial of the other
man it had not been made. By his threat it must be made.

Bob hesitated--and while he stood, undecided, the roar of a car, coming
at full speed, came to his ears.

He glanced down the road. Hardly had he located the direction when he
recognized the car. It contained--Mr. Parsons!

A man's head leaned out of the open window. To Bob, as he crouched back
into some ornamental shrubbery, the face was unfamiliar; but he saw it
was brutish, fierce, angry--and he impressed it on his memory.

"Here's your pop, now," the man called--and then he gave an exclamation
that Bob could not comprehend. Presently the light went out--and, almost
at the same time, while Parsons alighted in the parking place, Bob, near
the rear corner of the building, saw a form emerge from the kitchens and
race away down the yard toward the grove beyond.

"Griff!" muttered Bob to himself. "Griff--running tight as he can
go--running away from his father--to hide."

Watching, more interested in the new arrival than in the son, Bob
remained in concealment. But his mind was puzzled.

"Why?" he wondered. "Why--and what next?"




                              CHAPTER XVII
                        "THE CASE IS 'SEWED UP'"


Sitting on the Wright porch, early the next morning, Curt and Al
listened eagerly to Bob's recital of the past night's events.

"After Griff ran off--what, then?" Al demanded.

"A taxi came racing along and stopped at The Windsock."

"What did you do?"

"What could I do, except keep hidden and watch?" Curt's question brought
the counter-question from Bob. "The taxi door opened--and who do you
suppose jumped out?"

"Who?" Curt and Al spoke at once.

"The very man Al and I saw in the supply room."

"I saw him hail the taxi," Al exclaimed. "Everything is beginning to fit
together."

"Yes, it is," Bob agreed, "and, what's more, it fits tightly. As soon as
the stranger paid his fare he recognized Mr. Parsons who was halted on
the roadhouse veranda, watching. They began to talk, and stood there for
a minute."

"They knew each other!" Curt exclaimed. "They must be working together
to loot the supply room. That's probably how the mystery man got in: he
had a key from Mr. Parsons."

"It looks like that," admitted Bob.

"What then?" Al wanted the story. "Did they find Griff?"

"No--but the stranger saw his motorcycle. He got awfully excited about
it and he went with Mr. Parsons to look at it. They went close to where
I was hiding back of the shrubs, but they didn't say anything until they
were close to the motorcycle. They were too far away for me to hear,
then."

"I'd have crept closer," declared Al.

"Oh--yes! You would!" Bob was scornful. "Right out across an open yard!"

Al subsided, crestfallen.

"What then?" Curt asked quickly, to avoid any quarrel.

"They talked for about ten minutes--then the man made some notes of
things Mr. Parsons said--I wish I could have heard! Then he hopped onto
his motorcycle and rode off, and Mr. Parsons stood thinking for awhile
and then----"

"Yes? Don't keep us waiting. What?"

"Curt--he turned the car and went back toward town!"

"Didn't look for Griff?" Al had recovered his usual interest.

"No! He drove away. Griff must have been watching, too. He came out, and
shook his fist toward the roadhouse and then walked off, and--that's
all."

They discussed the incidents of the past night, coupling them with the
strange actions and uneasiness of Mr. Parsons and of Griff on former
occasions, riding, as they talked, toward the plant.

Barney's cabin airplane was again on the field, and as soon as they
arrived and he saw them, from an office window, Barney summoned them.

"Well," he greeted them, closing the door, "how goes the study of
airplane building?"

"Oh, we know how they lay down the framework for the fuselage and how
careful they are to see that every longeron and brace and strut and
guywire and turnbuckle fits exactly in place and is well fastened," Al
exclaimed. "And we've helped put on the wings and the tail assembly, and
Bob is going to help install an engine, today, and we will watch."

Bob laughed and Curt joined him. They saw the amused light in Barney's
eyes.

"Well--you asked!" Al defended his enthusiasm.

"It was just a 'polite opening'," Bob grinned. "Barney wants to know
about--other things we've learned."

Interrupting one another, they gave him the details of their
experiences.

"Hm-m-m! Well!" Barney's face became very serious. "So that's it!"

"What?"

Barney smiled at Al.

"The partner and his son are working with an outsider. I thought so. But
what about the brown 'plane? Any news of that?"

"We left it out entirely," Bob said.

"We disobeyed Uncle," Curt admitted. "Bob said Uncle wanted us to drop
things here and concentrate on trying to find the brown 'plane, but----"

"We can't find that 'crate' I feel sure." Bob was earnest.

"Not only that, but if a crime is being committed under your nose you
won't go off looking for something else to do while it is going on, will
you?" Al wanted their course confirmed.

"You did just right," Barney commended them. "You lads stick to this end
of it. I've suspected that Parsons and his son were 'up to' something,
and I don't agree with your father, Bob, about the brown crate at all! I
think you fellows deserve a 'raise' and if you can only catch one or all
of the crowd doing something--catch them 'red-handed' in a way of
speaking, I'll hand out a little private reward. I feel that it's due
to--to the memory of Mr. Tredway. He was mighty good to me and--and I
want to--get everything cleared up here, because I think the ones who
have been doing wrong right here at the plant got found out by him and
they either hired that airplane from some distant place and flew out and
rode down Tredway or else they paid some unscrupulous pilot----"

He paused as he saw Al squirming in his chair with eagerness.

"What is it, Al?"

"Unscrupulous pilot!" reiterated Al. "Why--the man at The Windsock is
a--an ex-pilot."

"Glory be! That's so!" Barney nodded.

"Well, from what I saw of him, his face shows that he's unscrupulous,"
added Bob.

"It looks to me, from here," Barney said, slowly, "it looks to me as
though we've got the case 'sewed up.' All you need to do is to find out,
some way, about that ex-pilot--what he does with his time, if he owns a
crate yet, and so on."

"You think?----"

Barney turned to Curt.

"I think," he nodded, "that ex-pilot might know a lot about a brown
'plane, and about what it did to force another one down----"

"Then we have got the case 'sewed up'," Al declared. "We came here last
night to see if we could compare a little scrap of writing we found
where the 'plane had been, with the books of letters and things to see
if the writing agreed."

"And what did you find?"

"We had no time to find anything," Curt admitted. "The other things came
up----"

"Let's see that note? Where is it?"

Al produced the much-folded, dirty scrap and handed it to Barney.

"No!" he shook his head after a careful study. "Don't recognize it!"

"The supply clerk?" hinted Bob.

"Not at all like his writing."

"Well," said Curt, "it's done with an indelible pencil. Now that we know
the ex-pilot is under suspicion, we can find out if he has an indelible
pencil that he carries around--or, he might destroy it, considering what
has happened since the note was written."

"But who's the note written to?" asked Bob. "It says 'everything O.K.'"

"To whoever hired him. To Parsons, maybe--or to Griff----"

"That's so!" Bob became very thoughtful.

"We ought to get a sample of the ex-pilot's handwriting," suggested Al,
eagerly. "Shall I? I can try! They don't know me out at The Windsock.
Couldn't I take my autograph album--and----"

"I'll make inquiries about the brown 'plane, from around The Windsock,"
added Curt.

"Then I can keep tabs at this end," argued Bob.

"Fine!" agreed Barney. "Fine! Yes, sir! Boys--we've got the case 'sewed
up' or circumstantial evidence never pointed true."

"Did you see Dad, again?" asked Bob as they rose.

"Yes, but he's awfully busy on that other case. He must trust you
fellows pretty well."

"Well," Al swelled with pride, "maybe we've disobeyed orders, but if
this comes out as good as we think it will, we'll have no trouble making
Father see that he was wrong and we were right to disobey."

"Right you are!" agreed Barney.

Griff seemed to be getting ready to work himself into danger for their
special benefit, it seemed to Bob in the engine assembling rooms. The
youth was angry, upset, uneasy, fidgety; he hurried out when he heard
his father's voice approaching down the hall and the older man betrayed
as much uneasiness and concern as did his son.

But that night, when they thought they had the last stitches taken to
"sew up" the case, as Barney said, Fate ripped out the whole thing--and
they were left without a thread of a clue!--until the unexpected thing
happened that gave Bob his "hunch!"




                             CHAPTER XVIII
                             A NEW MYSTERY


Cheerfully Al greeted the rigger for whom he worked.

"Barney--Mr. Horton--" he corrected his own familiar allusion to the
manager of the aircraft plant, "--says please hurry the work on this
sport biplane. The man who's buying it is in a big hurry. He wants to
get into some race with it."

"Oh, sure!" the rigger grumbled a little. "They're all in a hurry. But I
don't rush my part of it for anybody. There's been enough complaint
about this plant, already, without me doing anything to cut down the
performance of a crate by skimping my share of the high standards Mr.
Tredway always kept up."

"I know," agreed Al, "but he meant to do all you can, I guess."

"Yes," the rigger was in a complaining mood, "that's all very well. But
did he say why they're giving us cheaper stuff to work with, since the
real boss--went West, maybe!--did they tell you why that is, that we're
getting cheaper stuff!"

"No," Al admitted, "but I do know that Mr. Parsons and Bar--and Mr.
Horton were talking about some complaint from the wing assembling room,
about poor fabric. They almost quarreled. Barney told Mr. Parsons it had
to stop, he was going to uphold Mr. Tredway's ideas, and Mr. Parsons
said so was he."

"Well, somebody's ordering cheap stuff. Look here!"

He picked up a turnbuckle, a metal object in which the threads of each
wire end were so threaded in that when the ends of wires were screwed
in, the turning of the central, revolving part either drew the two
sections of wire close, making it taut, or allowed them to recede a
little from one another, for more looseness--by which the flying and
landing wires, and other parts of the guying rig were adjusted.

The turnbuckle looked all right to Al and he said so.

"Shows how much you know," scoffed the rigger, Sandy. "Look here--heft
this--and then this one!"

He selected another turnbuckle, handed both to Al, and the youth
"weighted them" in his two hands.

"This one does feel heavier."

"Of course it does! It's a cheap casting, not the aluminum alloy the
other one is machined from. Why, them threads on the new one will wear
and go bad in no time!"

Al, watching, observed that as the rigger manipulated a pocket knife in
the threaded end of the part, bright metal and a worn look were almost
immediately evident.

"Yes," Sandy Jim agreed with his discovery, "and I've been talking
around and others is dissatisfied--in the dope room, in the engine room.
Everywheres!"

"But when Mr. Parsons talked with the manager," Al explained, "they had
the supply clerk in and went over the orders and way-bills and delivery
check-up, and everything was all right. The orders went to the same
firms, as always----"

"We're getting shoddy stuff, all the same!" grunted Jim. "What good is
it to rush out a 'job' and have it accepted on the reputation of Mr.
Tredway, and then have complaints in a few days?"

"I don't know," said Al, and changed the subject. "Mr. Horton says
you'll have to excuse me, this morning. He's sending me out on an
errand."

"Oh, sure!" Jim snapped. "Wants this job rushed, and takes away my
helper! Whyn't he use his office boy?"

Al could not explain that it was Barney's way of releasing him so he
could go to The Windsock for that comparison of the ex-pilot's autograph
with the clue note Al held.

"I guess you'll have to ask him," Al grinned, and went over to get his
bicycle. Sandy Jim followed him, dragging a small parcel out of his hip
pocket.

"As long as you're riding," he suggested, "go past the house and slip
this in to Jimmy-junior. It's some odds and ends of broken stuff for him
to use on his new model air-liner."

"Glad to," Al took the parcel.

"Get back quick as you can," urged Sandy. "I need a good helper."

Al quickly sent his bicycle along the highway. Stopping at Sandy's home
he took as little time as he could to drop the parcel, and to explain to
Jimmy-junior that the reason he had not yet been taken into the Sky
Squad was that they had been too busy, evenings, to hold any meetings.

Then he made his way to the roadhouse near Rocky Lake Park, and leaned
his wheel against the veranda supports.

"Is Mister Jones busy?" he asked a sleepy waiter who was listlessly
dusting off some chairs in one of the small compartments made to look
like the cabin of an air-liner. Al had found it easy to learn the
ex-pilot's name.

"In the office," the man jerked a thumb toward a side room. Al, knocking
at the door and hearing a gruff voice bid him enter, went into the same
room Bob had described as the scene of the quarrel between the roadhouse
man and Griff.

The man, looking up from some work at a small desk, had a coarse,
scowling face. No wonder he was "ex" pilot, Al reflected, with a face as
brutish and a manner as unfriendly and curt as "Mr. Jones" showed.

"What's wanted?"

"Why--er--" Al stammered, not so much ill at ease as trying to pretend
he felt shy in the presence of a great man, "I'm one of the fellows who
have a sort of club, to study airplanes, and all that--and I--we--heard
about you being a clever pilot, and I thought I'd ride out and ask if
you'd be generous enough to write a little something about aviation in
our club autograph album." He produced the small book he had brought in
his coat pocket.

"Hm-m!" The man scowled. "Le'me see that book!"

He took the small volume and Al's heart sank. Instead of writing
sensibly and generously on blank page invitingly offered, he flipped the
pages, and Al knew that the affair was a failure. There was nothing
about aviation in the few autographed verses and sayings already
collected.

"That's no aviation album!" The man thrust it away angrily and jumped
up. "What's your scheme, young fellow?"

"Scheme?" Al tried to look innocent. "I told you--we want to get you to
start the real autographs from aviators!"

The subterfuge did not satisfy the man. He frowned, stared at Al as
though trying to get through his guard, to discover any hidden motive.
Al, inexperienced, fidgeted, unable to conceal his uneasiness.

However, he received a surprise.

"Sure!" The man snatched up the book. "Come to think of it, why not?
Fact is, kid, I'll start you off with _two_ autographs. Wait!"

He hurried out of the office. Al did not dare "peek" to see where he
went or what he did. For all Al knew, the man might be just beyond the
side door, watching. He sat very still, trying to be as self-possessed
as he could.

Presently the man returned, with the book held open.

"Here y'are!" he said, affably. Al, glancing at the book, saw that two
opposite pages bore fresh scrawls. The man waved a hand. "Welcome. Run
along, now. We're busy, here--getting set to open up a new 'airport' out
on the side, where folks can dance to a fine orchestra in a hangar. Tell
any of your friends you like--especially your parents. We got the
prettiest imitation of an airplane for the orchestra to set in----"

Al, hardly able to mumble his thanks, dashed out to his bicycle. He
could scarcely hold in his impatience. One of those sets of rough
characters was written with a pencil, the other with an indelible
pencil!

One had a familiar character to its shaping of letters!

A little way down the road, near the lake, where the airplane had
cracked up, Al drew his machine in under a tree, almost tore the book
out of his pocket and opened it hastily.

On one page was a maxim, exactly what a pilot might write:

"Knowing when to stay on the ground makes a better pilot than knowing
how to get off it!" It was signed with initials--"T. J." Al did not
recognize the writing although, he understood that the saying meant that
a pilot wise enough to be cautious was better than one who thought that
getting into the air was all there was to flying.

The second page revealed one word, the pilot's good-luck wish, and two
initials also:

"Tailwinds! J. T." it told him.

"T. J. and J. T."

Hurriedly Al drew out the folded, ragged, dirty little note--his clue.

It exactly corresponded in every character with the short autograph!

But!----

Who had written the autograph? Had Mr. Jones? If his name was Jones he
would have signed the initials on the first autograph--"T. J." Or--would
he have signed that way? Might he not have signed the reverse? Had he
written either page? Who else had helped?

More mystery! And no way to solve it!




                              CHAPTER XIX
                            TANGLED THREADS


On a former occasion Bob had related news to an audience composed of Al
and Curt.

As the trio rode homeward, Curt to share supper with the brothers, Al
was the spokesman.

"Did you ever see so many people to suspect and so many clues that don't
lead anywhere?" asked Curt when Al had told his story and had shown his
evidence.

"The Sky Squad has a mystery, and there's no mistake about it," declared
Al. "We got what we wanted, but now--what can we do with it?"

"You mean the mystery?"

"No, Bob. I mean the autograph."

"Well, it proves one thing, anyway," Bob asserted. "The single word
matches our 'Everything O.K.' note. That proves that the man who wrote
the note is at that roadhouse, The Windsock."

"It does," Curt agreed. "But--is it the man named Jones? Did he write
it?"

"Did he write either one?" Bob was puzzled as he spoke.

"He left the room, you said." Curt turned to Al, who nodded.

"Maybe he didn't write anything!"

"What does all that matter?" Bob said. "The point is that we have proof
that the man who used the brown 'plane is staying at The Windsock. Now
our job is to discover who he is."

"Let's see those autographs again." Curt drew his wheel to the roadside
and took the book from Al. "'T. J.' is written with a plain leadpencil,"
he remarked. "The 'J. T.' one is the one written in indelible pencil.
'J. T.'" he repeated thoughtfully. "Do you suppose Jones transposed his
initials and then got a waiter or a clerk to write the other and sign
what Al would take for his initials?"

"It's too tangled up to suppose about," argued Bob. "Two things we do
know from it."

"One is," Al remarked, as they resumed their ride, "one is that we know
the brown airplane man is at The Windsock. What's the other?"

"Well, whether it's Jones or not--Jones has something to hide, this
proves. Otherwise he'd have scribbled a word or two for Al, and thought
no more about it."

"That's so."

"It simplifies things, doesn't it?" Al, speaking after Curt's agreement,
was not so sure as his words indicated.

"It makes them more complicated," Bob retorted. "Let's see what we know
and where we stand."

As they rode slowly, he tabulated their clues and theories and
discoveries, with many interruptions from his companions.

"First of all," he began, "we saw a mysterious brown airplane hidden in
the woods. Then, when we went there, it was gone--and this note was
flung aside. The crate took off in a hurry because we saw heavy tracks,
and made in a hurry, by the way they looked. Then there was a crack-up
at Rocky Lake and we found out Mr. Tredway was in the Silver Flash that
crashed."

"And we saw a man come to try to help, swimming across the lake," Curt
broke in.

"And then we met Barney and he and Father called us in to help solve the
Mystery Crash," added Al.

"We learned there was more mystery than just the fall of the crate," Bob
went on. "That was bad enough; but there was more! Parts were being
stolen from the aircraft plant, and 'planes had been tampered
with--after tests showed them to be perfect!--and----"

"When we went there to work in the plant," Curt was eager to add his
contribution to the sum of their recollections. "We saw Mr. Parsons
acting suspiciously, and Griff, too."

"And we have suspected Langley was in bad company with Griff, and Lang
got mad at us about Griff--but we haven't found any reason to suspect
Lang, since," Al declared. "But now we've got more people to
suspect--the stranger who came to the plant and this ex-pilot."

"But all this hasn't brought us any closer to knowing anything
definite," Bob objected. "I begin to wonder if Father was right, after
all, when he told us to 'drop those unimportant things and locate that
brown airplane.'"

"But we can't!" defended Al. "There's no way to start hunting. I'm for
keeping on disobeying until something happens to help us."

"And I'm for getting in to supper," Curt changed the subject as they
dismounted at the cottage. "Let's give what brains we have a good rest
while we eat."

"Well, one thing more and we will." Bob paused, thoughtful and serious.
"Al said we had no cause to suspect Lang. Well--today, I was wondering
why Griff was so nervous and fidgety and furtive, and Lang came in and
took me out, to give me a lesson in handling the controls, he hinted. He
really did, but before he took me up while he tested the new sport
speedster, he said, 'I see you're bothering Griff again,' and he gave me
'down the banks' about it."

"What's suspicious about that?" Curt asked.

"Not that, so much. But--he told me to go on home, that it was closing
time, and I put on my cap and punched the time-clock, and then I
recalled that I had left the baseball we were playing 'catch' with at
noon, in my bench drawer. I went back, and there was Griff, all excited,
and Lang, with his head close to Griff's, acting as upset and as uneasy
as Griff when I came in and surprised them. Lang snapped at
me--I--don't--like it----"

"Well," Curt was quiet, a little hesitant, but firm. "If Lang is mixed
up in something wrong--we ought to--at least we ought to try to save
him!"

"That's good," agreed Bob, quickly. "I thought you were going to say 'we
ought to catch him with the rest.'"

"No, indeed, I think more of Lang than that."

"But how could we save him?" asked Al.

To that they had no answer as they went in to eat.

As they sat at the table Al mentioned the morning's chat with
Jimmy-junior, and suggested that they really ought to go and spend an
evening with him as he had urged them to do; if the others liked him,
they could communicate by nods and take him into the Sky Squad, not as a
full member, but just to please him and have a fourth member to call on
if an emergency arose where he would be needed. Al vouched for his
innocence and good nature, eagerness to please and willingness to work
without asking for explanations of why he did a certain thing.

"He'd be a good one to send to watch anybody--Griff, or the ex-pilot,"
Al spoke as the trio rode toward Jimmy-junior's home.

"We'll see----"

Bob did not finish. He applied his coaster brake, made a quick signal
for silence, swerved into a garage driveway, followed by his companions,
and dismounted, dropping his bicycle on the lawn.

"What happened?" asked Al, thrilling to some possible mystery.

"Lang turned the corner!"

"You didn't want him to see us?"

"Certainly not!" Bob answered Al.

"Wonder where he's going." Curt slipped along the side of the house by
which they had stopped. "He's in a terrible hurry," he reported, coming
back. "In a second he'll be passing this house. Get back--behind the
house. I don't think he'll notice the bikes on the grass in the dusk."

They hid from the view of anyone on the sidewalk. Peering cautiously out
in turn they saw Langley hurrying by.

"Now--where's he going?"

"And what shall we do about it?"

"See where he goes," Curt answered the other two.

Lang turned the next corner.

"I'll bet he's going to Griff's house!"

Al was correct in his guess. As they trundled their bicycles, keeping as
far behind Lang as they thought necessary, they saw him turn in at
Griff's gate. Five minutes later, from carefully chosen points of
concealment they saw Lang come out, take Griff's repaired motorcycle and
ride off in haste.

Consulting one another with dismayed eyes, the chums, by common consent,
mounted and pedaled for dear life along the street, around the corner,
back to the main highway.

They seemed to sense where Langley was going.

They did not, however, divine what he planned to do!




                               CHAPTER XX
                           A PACKAGE OF MONEY


Before they reached the aircraft plant toward which they pedaled with
all their power, Bob, Curt and Al saw a light flare up.

"That's the flying field ready for a hop," panted Al. "Hurry!"

"Do you think it could be Lang?" Curt asked.

"Who else?" Bob retorted, pedaling faster.

"There's nobody at the gate," Curt called. They were near enough to see
the open gateway.

"The watchman's helping with chocks and spinning the prop."

Bob, increasing his pedal revolutions, forging ahead, spoke over his
shoulder.

"Wait!" called Curt. "What are you going to do?"

"Find out----"

"No! Wait!"

Bob slowed up his pedals, permitting the bicycle to coast along as the
modern, free-wheeling automobile runs when the foot is removed from the
accelerator pedal. Curt caught up to him. In a moment, as they
approached the gate, Al came up also.

"Don't let him see you at all," warned Curt. "Better wait and ask the
watchman after he's gone. You'll find out more, that way."

It was good advice, and Bob agreed to act on it.

They hid the bicycles, in case it turned out that Lang had not left the
ground. Careful not to disclose themselves, they watched at the gate as
the engine of the sport model owned by Griff was warmed up. In the flood
of light on the runway they recognized Lang as the pilot, and watched
him adjust flying helmet and leather jacket, get into the craft, test
the instruments, checking carefully, and then get his wind direction
from the windsock, which told that the light Summer breeze was from the
South. The watchman swung the tail around, set the chocks again for a
final test. Lang "gave her the gun," to see if everything was hitting
perfectly, signaled for the chocks to be removed, and since his craft
was correctly headed into the wind the airplane taxied, gaining speed,
and rose swiftly into the dark.

Hardly waiting for the flood to be extinguished, the trio of amateur
detectives hailed the watchman.

"Too late to see Lang take off," greeted Bob. "He didn't say why he
hopped at night did he?"

"Yeah, he did! He's going off to see his uncle about something."

"That's funny," Al argued, under his breath, to Curt.

"Certainly is," Curt agreed.

"Thanks," Bob spoke to the watchman. "As long as we're here," he turned
to his chums. "Let's bring in our bikes and get some more of those books
on metal alloys Barney told us about."

"The boss is here, himself," the watchman explained. "Go ahead."

Barney was working late!

"His office is lighted," Al commented. "Let's stop in and tell him about
the note and the autograph."

"And about Lang."

"He must know Lang hopped off," Curt told Bob.

"Yes--the crate made enough noise--unless he's awfully busy."

Barney was busy enough, but he had heard the take-off, he admitted.

"I'm trying to check up on the firm's books." Barney waved a hand toward
the pile of heavy volumes, ledgers, daybooks, indexes and others,
scattered on his desk. "I can't find out what way they're doing it, but
something's being 'worked' about the materials."

"So Sandy told me this morning," Al stated.

"Well, I can't find it," he pushed three of the smaller books into a
large lower desk drawer, and turned, mysteriously smiling. "How do you
like this idea?" he asked. "I'll put a few books aside, and then, when
the staff comes in, tomorrow, I'll see how the bookkeeper and Parsons
take it. If there's anything 'flim-flammy' about them, they will show it
when they miss the books."

"That's dandy!" agreed Al.

"What do you figure on doing now?" Barney asked.

"Why--nothing special," said Bob. "We thought if Lang was flying over to
see Father, that would take him about three hours--or four, and he
wouldn't get back here before morning, so there's no use waiting for him
to come back here. But--we haven't anything special to do, except go to
call on Sandy's son, Jimmy-junior."

"Why not 'stick around' here?" suggested Barney. "For awhile, at least.
I don't want to be mixed up in anything, but if anybody should come
slinking around, I'd like to know it--as long as you have nothing much
on hand?"

"Let's!" urged Al.

"Suits me," Curt agreed. Bob was willing.

"Why not put out all the lights, and just hang around in the dark for an
hour?" suggested Barney.

They agreed readily enough, and felt quite like conspirators or real
sleuths on a big case as they occupied easy chairs in the big
"directors' room" and talked in low tones.

Their vigil was soon rewarded.

Footsteps, sounding without effort at concealment, in the corridor,
caused all three comrades to become tense and alert.

Bob felt a hand clutch his arm, and almost called out in his nervous
reaction until he realized that Curt was whispering:

"Hide!"

Al, already at his other side, was anxious.

"How? Where?" he said quickly but softly.

"Behind the chairs."

However, hardly had they gotten into concealment when they realized that
there was no need to hide; the steps went briskly past the door and on,
down the hallway.

"Now what?" asked Al as a door opened and slammed.

At the door to the hall Curt turned, waiting until the other two joined
him, he spoke quietly.

"You wait here," he urged. "I'm lightest--and quickest, I think. Let me
go on down and 'snoop' a little. He slammed the door so hard it jumped
open a little--it's Barney's office!"

"Barney? He--do you suppose?--" Al was puzzled. "He told us to wait,
though----"

"It's never Barney. I'll soon see----"

Curt was gone, tiptoeing, clinging close to the inner wall, where, he
felt sure, the boards were so sturdy and well secured that they would be
unlikely to creak.

In suspense his companions waited.

Soon, in the dim hall, they saw Curt returning.

"It's--it's--Mr. Parsons!"

"What's he doing?" Al was eager.

"Hunting for something."

"Those books, I'll give you odds on it!" Bob spoke softly.

They waited, uncertain what to do--in fact, there was nothing they could
do but wait.

They had only a moment to decide. Down the hall, from the stairway, came
other steps; the chums drew back inside the doorway. They let Curt peer
out.

"It's Griff, this time!" he informed the others. "He's coming to meet
his--no he isn't! Get back! Hide!"

Hesitating steps paused but before there was any further movement Curt,
Al and Bob were well screened from any but a careful search in full
light.

They were glad, this time, they had gotten under cover. Griff did not go
to meet his father!

Instead he came into the directors' room, at least as far as inside its
door, where, a faint blotch against a very dull oblong of weak light,
Bob saw him standing, watchful.

"Shucks!" thought Al, "we can't find out about Mr. Parsons on account
of----"

They did not hear anything; but evidently the youth watching at the door
did, for he came further into the room. Would he decide to hide? Might
he choose the spot already occupied by one of the youths?

Their suspense was relieved! He waited inside the doorway, and it was a
wait of a long, dragging three or four minutes that seemed like an age
to the crouching trio; but finally he walked out, his step confident and
loud, showing that need for concealment was over.

Quickly the three reached the door. Already, as they peered out, a light
was glowing, but not electric ceiling domes--it was a pocket flash held
close to something in Mr. Parsons' own office.

Like shadows the three, arms touching, went down the hall. They could
not contain their suspense. At an open door, partly drawn shut but not
locked, they stopped. Looking through the crack, hardly daring to
breathe or move, they saw Griff fit a key to his father's desk, open it,
take something from a small drawer--and walk confidently, if slowly,
to--the safe in the corner!

Before it his light was held low, close. He was manipulating the knobs
of the combination. As the partner's son he had access to it, the chums
realized. They forgot some of their caution but not all; they peered
closely in through the crack of the door--and saw----

"Phew!" breathed Al, "he's got--a package--of--money!"




                              CHAPTER XXI
                          CAUGHT AND CLEARED!


Spellbound the three watching youths saw Griff count the bills in that
packet he had taken from the aircraft plant safe.

They heard the ruffle of paper as he ran through the ends of the crisp,
new bills.

Then he stepped out of their line of vision.

With unexpected promptness, startling his companions, Al flung the door
inward so that it banged against the wall. Instantly he leaped into the
room. His chums followed. Startled, dropping his packet, Griff swung
around to stare in amazement and terror.

"Drop those bills!" Al cried needlessly, "we've caught you red-handed!"

All three of the Sky Squad were in the room.

Al dashed across to the window, to block any possibility of Griff trying
to drop the ten or fifteen feet to the ground. Bob snatched up the
money. Curt blocked the door.

After his first look of stunned horror, Griff sank into the swivel chair
and buried his face in his hands. His shoulders shook with a sudden
revulsion of feeling that unmanned him, made him sob like a creature in
pain.

For a moment no one moved. The comrades were rather dismayed and
nonplussed by Griff's pathetic attitude.

They had caught him, yes! Red-handed, as Al had said, they had caught
him, in the act of something very dreadful.

Nevertheless, his surprising way of giving in, sitting there in a bent
posture, with his body racked by his sobs, made him a rather pitiful
figure.

"Stop that!" Bob said, finally, and rather gruffly. "You've done wrong.
You've been caught. Take it like a man!"

"Yes," Griff replied in a shaking voice. "Yes--I'm caught. I know I'm a
baby--but--but----"

He fought back his weakness and gulped.

"But--what?" demanded Curt. "I suppose you'll say you were forced to do
this by somebody else. They always do, in books!"

"No," Griff answered. "No. I--it's all my doing. But----"

"Why do you keep saying 'but'?" asked Al.

"Oh!" Griff had hard work not to break down again. In spite of the way
they had found him, in spite of what he had been planning to do, there
was something that touched the youthful hearts of the trio, in Griff's
sorrowful eyes and drawn face.

"Oh!" he repeated, "if only somebody could help me instead of hounding
me and----"

"We're not 'hounding' you," Bob defended their action. "You'd have done
the same."

"But you've been watching me and following me and suspecting me," Griff
declared sadly. "I know I deserve it--but----"

"Oh! Stop saying but!" Curt was annoyed by what he took to be an attempt
to win sympathy. "We'd have helped you, instead of 'hounding' you if
you'd been honest, instead of trying to be cunning and in with the wrong
sort of people."

"Oh, yes, you would!" retorted Griff, bitterly. "That's easy to say."

"Well, it's true," declared Bob stoutly.

"Nobody helps me," responded Griff. "Everybody is after me for one
reason or another."

"That's because you're so furtive and fidgety that you ask for it--and
doing things--like this--" Bob shook the bills.

Griff sat in silence for a moment. Bob walked over to the open safe, saw
where the package belonged, and pushed it into place, then slammed the
safe door, turned the knob of the combination to lock it and swung back
to Griff.

"There!" he exclaimed. "That shows we're helping you."

"I--I--what do you mean?" Griff stared.

"I mean this!" Bob came and stood in front of him. "I mean that the
money is back in the safe. If you can show any reason besides temptation
or somebody forcing you to do--this!--we'll all promise to say nothing
more about the things we saw you do."

Griff shook his head.

"That wouldn't do any good," he said despondently. "I've got to have
that money. You think it's--" he could not bring out the word, but he
saw that the trio recognized what he meant. "It isn't--because Lang is
flying, right now, to his uncle, to get him to come back and give me
money--a loan--to replace this."

The chums exchanged surprised, wondering glances.

"Lang! Going to Father for money for you?"

"Yes," Griff answered Al. "It's--it's all mixed up and--awful!--but you
say you'd help instead of telling on me, if I could show I wasn't as bad
as you think."

Bob thought he saw a genuine honesty in the clear look Griff gave him.
His sympathy was really quick and he wanted to be fair.

"You could count on that!" he stated earnestly.

"You bet you could!" Al declared and Curt added a similar assertion.

"If I thought you meant that--if I thought you'd believe me----"

"Really we would!" Al was also touched; Griff, caught and breaking down
and seeming to be declaring innocence in some way, was not the furtive,
uneasy, shifty-eyed Griff they had known. "Honestly! Try us and see." He
and Curt moved closer. The three stood in a group in front of the
huddling youth in the swivel chair.

Griff looked up dolefully.

"It will make me out bad enough," he stated. "But--not as bad as you've
been thinking. Oh, I know!" he took on a touch of his old defiance, "I
know you've tried to connect me with all the wrong things that have been
going on here! I know I've acted as though I am guilty. I'm not,
though--not in the way you think."

"All right," Curt admitted. "We'll listen. We'd rather have you innocent
than guilty--of anything!"

"Even if our case--" Al stopped suddenly, but Griff nodded.

"I guess you all think you're clever," he said, forgetting his own
trouble for a second or two. "You come here to learn all about this
mystery of where the missing parts go and who did things to the crates,
and why. Don't you think we have eyes? It's all over the plant what you
are trying to do. Don't you suppose we all know one of you is a close
friend of the other two, and Bob and Al are sons of a detective? What's
the answer?"

"The answer seems to be that you thought we weren't smart and so you
went right ahead." Curt was a little nettled by Griff's statement,
although common sense told him, now that Griff mentioned the point, that
their scheme must be fairly evident to any sensible person.

"I didn't think whether you were smart or dumb," Griff replied. "I had
too much on my mind. Bad as it is, it might as well be confessed. I
gamble, and owe money for it, and I came here to borrow this from the
safe--it's as much my father's as anybody's, because he's Mr. Tredway's
partner, but--I didn't intend to try to 'get away' with the money. I
only wanted it overnight. Before the office opens Lang will be back with
the money to replace it."

"What makes it so important to get money at this time of night?"
demanded Curt, suspiciously.

"I guess I'd better tell the whole thing."

"We're listening!"

"Go ahead. Tell us!"

Griff nodded. Dejectedly, shamefaced and humble, he related his story:

"I've been running around with a pretty rough crowd," he admitted, "and
they got me in the habit of going to places like The Windsock, out on
the----"

"We know!" Al interrupted impatiently.

"All right. There's ways to gamble, out there, if you know the people
who run the place."

"Jones?"

"Well--he owns it, yes. Mostly its Jenks, his manager, and the waiters
that let the crowd do things outside the actual license rights of the
roadhouse. Well, anyhow, I got to spending money pretty fast and I
gambled. After awhile I lost so much I found out I was owing the 'house'
as they say, more than two hundred dollars!"

Although several maxims and Biblical quotations sprang into Bob's mind,
he kept silent. This was no time for preaching, for pretending the
"holier than thou" pose. Under the same temptations, argued Bob to
himself, it would be hard to say whether he'd go Griff's way or not. It
isn't how good a fellow thinks he is, but how good he proves himself to
be under temptation, that counts, Bob decided.

"That's what you're taking the money for--or trying to," Curt
determined. "But why did you have to take it this way, and at this
time?"

"The manager at the roadhouse said, last week, he'd have to get all the
debts owed the house and clean up, because they're spending a lot on a
new dance place, like a----"

"Hangar. We know. Never mind why they wanted it. Tell me," Bob changed
the subject for a moment, "what does the owner look like? Is he short,
thick-set----"

"That's the manager----"

"But that man let on to be Jones." Al broke in.

"Maybe he did? What were you doing there--snooping?"

"Never mind," said Curt, pacifically, wishing to get Griff's side of the
matter first. "We wanted a specimen of his handwriting----"

"I wish _I_ could get one!" declared Griff, ruefully. "That's the whole
trouble, fellows." His manner was more eager, more confidential. "I paid
the money once--and he didn't give me a receipt----"

"Oh!" Bob was connecting some things in his mind. "He came here one
evening and demanded the money, and you gave him a parcel and then
realized he didn't give you a receipt. You tried to chase him on your
motorcycle and got into an accident."

"I thought you were watching, but I was too excited and upset to care,"
agreed Griff. "Yes, I had borrowed from all the fellows I knew, and had
scraped every cent out of my savings account, and I had the money. But
he didn't give any receipt, and when I finally got over the smash of the
motorcycle and went to ask for it he declared I'd paid him with a
package of wadded, folded paper and not money!"

"But it was money," declared Bob. "Unless you changed it, because I
caught you wrapping up something green the day I came into the engine
assembling room."

"It was money, all right enough," Griff asserted. "But he wanted it
twice. Well, I had promised my father that I wouldn't go with that crowd
any more, and I had been weak and went against my promise. So I couldn't
go to him about it."

"If you had, and made a clean breast of it, he would have gotten you out
of this scrape." Bob had to say that much.

"I don't think so!" Griff was morose. "He's got so much worry on his
mind about the plant and all that's happened that he's jumpy and nervous
and suspicious and he'd throw me out of here, and maybe send me away
from home. And I am trying to go straight. I will--I make a vow on
that!--if once I can get out of this scrape. I've learned a lesson."

"But that fellow at the roadhouse knows you're afraid of your dad, I
guess," asserted Curt.

"Yes, and when I said I had paid the money----"

"I overheard that," Al stated, and related what he had heard through the
open office window at The Windsock.

"You fellows have been on the job!" There was a note of admiration in
Griff's voice, then he sobered and went on. "Yes, that fellow, out
there, knows about me being afraid of Father, and he said if I didn't
have the money tonight, before midnight, he'd tell my 'old man' as he
calls Dad. They're opening a dance place and he said the cash was
essential tonight."

"So you told Lang and he went to get it," ended Curt for him.

"Yes, and he's going to call me, long distance, as soon as he gets
there, and I was getting the money out so I could start for The Windsock
the minute he calls up."

"What's your father doing out there so much?" demanded Al, suspiciously.

"Trying to 'get a line' on me, I guess!"

Curt turned to his comrades with a rueful grin.

"That explains everything," he stated, almost regretfully. "Griff has
cleared himself, and his father's motive is logical."

"It leaves us 'up in the air'--and not in any 'crate' either!" agreed
Al.

"Yes," nodded Bob. "Barney said the case was all sewed up--but the
threads must have been weak, because here's our case all torn apart!"

"Well," said Curt, "for my part--I'm glad!"

Since Griff and Mr. Parsons were cleared of suspicion, the other two
agreed promptly.

"I may be cleared," said Griff sadly, "but I'm not out of trouble. If I
don't get this money to that man--Jenks is what we all call him, Toby
Jenks!--why, he'll call up Dad--and then----"

"We said we'd help if you could clear yourself," stated Bob.

"And we will!" agreed Curt.

"With all our heart!" added Al. "But--how?"

"Let me take the money out there!" urged Griff. "Just keep quiet about
catching me here----"

"Even if the money belonged to your father, which the stockholders of
the corporation might argue out with you," said Bob seriously, "taking
it, just overnight, would be--wrong, to say the least."

"Why don't you go to Mr. Parsons--to your father?" suggested Curt.

"He's got all this worry on his mind, trying to see what's wrong----"

"Yes," admitted Al, "I guess it would be better not to worry him about
this, if we could see how to get around it and still not let you take
this money."

"We suspected him," Curt said, rather ashamed but anxious to be as frank
as Griff, whose manner and actions convinced them that he had been
absolutely honest with them. "We suspected him of being mixed up in
something."

"Everybody suspects everybody else," admitted Griff. "Dad suspects
Barney, Barney suspects me, I suspect the supply clerk and the
bookkeeper of working together to get cheaper supplies here, and they
suspect each other and everybody else--even you three!"

"Well," Bob waved the statement aside, "that isn't getting down to brass
tacks. Think, for five minutes, everybody. We've got to help Griff!"

Seeing their case destroyed, their chief suspect cleared, they turned
loyally to help to retrieve themselves by aiding him.

For five minutes no one spoke.




                              CHAPTER XXII
                          THE "MYSTERY CRATE"


"Father ordered us to drop this part of things," said Al finally, "but
I'm glad we disobeyed if it helps Griff to get out of trouble."

"So am I," admitted Bob. "But that isn't what we were quiet for, to talk
about what we've done."

"We want to know what to do!" Curt commented.

"That's what I was coming to," defended Al. "Let Griff stay here with
you, Bob, while Curt and I ride out to The Windsock. We can call up as
soon as we arrive, and then wait outside, hiding. Then Griff can take
this money and come out, and pay it, and then we will jump in from
outside the door and grab it and jump through the window and----"

"Is that the best you can do?" scoffed Curt. Al grinned.

"It looked good till I said it," he admitted, "then----"

"That's you, all the way!" his brother challenged. "Quick on the trigger
and sorry when the bullet hits the wrong target."

"I have a plan, though," suggested Curt. "Al and I can go out to The
Windsock, as Al said, to get a good place under that office window.
Then, when Griff pays the money, we will be witnesses, and if the man
tries not to give a receipt we'll be on Griff's side."

"Better, but not perfect," said Bob.

"I suppose the head Sleuth of the Sky Squad has the one perfect plan!"
Al was sarcastic.

"No," Bob was honest, "I haven't! I thought of having Griff call the man
and say he'd be there bright and early with the money----"

"I did tell him that, when Lang left. He said it would be tonight,
whether he got it from me or from my father."

"Um-m-m!" Curt was thoughtful. "Bad! Well----"

"If we could keep that Jenks man so busy, keep his mind so much occupied
he'd be too excited to think about Griff--" Al was not very sure of
himself.

"We could!" Curt astonished Al by accepting the idea. "Look here! If he
isn't the ex-pilot, maybe the ex-pilot wrote that other autograph.
Whether he did not or did, anyhow the Jenks man had something to
conceal, or he wouldn't have gone to the trouble of giving Al two
specimens of writing to get mixed up with. Now--if we were out there,
and Griff tried once more to stave off payment till morning, if he
agreed, all right, we could come home and this money in the safe would
be all right."

"Logical so far," agreed Bob.

"All right. If the man refused to wait, we could telephone in to Griff
to find out, and if Jenks refused to wait, we'd walk in on that Jenks
fellow and say we knew he was mixed up in something wrong about the
airplane crash, and throw out hints, and so on. I think, myself, he is
in it somehow. He'd bluster, maybe, but if he has anything to conceal,
we could scare him, and then tell him to let Griff alone for the present
or tell his story to a policeman--and we might hint that he could
explain a lot about the crash----"

"I like it as well as anything you've suggested," said Griff. "If you
could 'get way with it.'"

"Trust us to scare him good and proper!" declared Al. "I'd ask him 'how
about the brown 'plane'----"

"No good," argued Bob. "We looked that craft up in the official registry
and she's from out West, and while we know her markings we haven't found
her and I don't believe he----"

"I do," Al defended his deduction. "I think he had it brought here for
him to use, and then taken away again, and that accounts for his
note--'Everything O.K.' when the pilot left it there and he put the note
on the seat to show he had been there!"

"Then maybe this Jenks hopped off, in the morning, met the 'plane Mr.
Tredway was flying, forced it into trouble, rode it down----"

"But we saw the big cabin ship!" objected Bob to Curt's theory. "There
was no other ship around."

"You can't be sure!" argued Al. "That brown crate might have been up
above, against the dark clouds in the sky! You couldn't tell if we heard
one or two engines. He could have surprised Mr. Tredway, could have
driven him into a dive--something may have gone wrong----"

"But Barney examined the craft when it was hauled in," urged Bob.
"Nothing was wrong with it at all!"

"Well," Al was obstinate, "I think what I think!"

"Who owns the brown 'plane?" asked Griff. "Did you look that up?"

"Yes, we did! No name we know. No one mixed up in the case. It was
probably hired by wire, or telephone, from somebody we don't know."

"It isn't important, anyhow," Curt declared. "Not right now. What do you
think of my idea, Griff?"

"I'm for anything that will tide me over till Lang gets back."

"Then--let's do it!" Al jumped away from the group and was already at
the door. Bob hesitated a moment, then, seeing how eager Curt was to
echo Al's enthusiasm, he agreed.

After the two started for The Windsock, Bob sat with Griff, giving him
the facts they knew, the theories they had formed for awhile.

"It's tangled up, and no mistake," Griff, recovered somewhat, but no
longer fidgety, feeling that aid was being given him in his trouble,
rose. "Look here, Bob--I was so excited, I didn't eat any dinner. What
say you stay here in case a call comes in, while I run out and get some
coffee and sinkers?"

"Lock the desk first! I don't want to be caught here with it open."

"Right! I shan't need the slip that has the combination on it, any
more." He put a paper in a small drawer, closed down the roll top,
adjusted his cap at a more confident, rakish angle, and sauntered out,
while Bob made himself comfortable at the desk in the swivel chair.

The minutes dragged along.

In the deserted office building there was almost no sound--a rat crept
toward a wastebasket, ran back as Bob moved in his chair; but otherwise
the place was very still.

"There's an airplane engine!" Bob mused, as, in the silence, he caught
the faint, steady drone coming from the sky.

It grew louder--rapidly, much louder!

"It can't be Lang, coming back!"

Bob went to the window. The sound seemed to come from the other side of
the building. He ran across the hall into the directors' room and got to
the window, which had a fire escape stairway outside it.

Just as he peered through the bars of the fire escape, he saw a craft
swoop down, quite low. It did not land! Instead, it seemed to zoom along
and to rise swiftly.

"Overshot the field," Bob mused. "Why doesn't he drop a Verey light to
signal the watchman to turn on the landing floods? Or--maybe the
watchman isn't out there. I'd better see."

He ran down the stairs and out into the yard, across it and onto the
small landing field. The craft had passed, but he could still hear the
engine. It seemed from its change of location, that the craft was coming
around in a spiral.

Bob ran toward the switch controlling the flood lights. One of the
large, hooded lamps was near it. As the sound of the engine came closer
he switched on the floods.

To his surprise the sudden light seemed to startle the pilot--at least
the craft seemed to waver, to skid, to drop, and then, to catch its
flying speed and control. But it did not spiral as he expected a pilot
who had waited for light would do.

Instead it began to climb.

Swiftly, eagerly curious, Bob caught hold of the handle on the adjusting
mechanism of the flood light. It could be lifted, or set lower, to
govern the range and height of its beam.

Bob proposed to use it as a searchlight, to illuminate the craft if he
could swing the heavy lamp upward in time.

Eagerly he labored with the mechanism.

Slowly the beam lifted.

Its intense rays caught the craft's underwings.

"What's going on here?" The watchman ran up.

For answer Bob pointed excitedly toward a brown, sharply outlined craft,
climbing, growing dim in the fainter beam as it receded.

"It's--it's--" he gasped, "--it's the mystery crate--the brown
airplane!"




                             CHAPTER XXIII
                              BOB PURSUES!


Realizing that the watchman did not know what he meant by "the mystery
crate," Bob hurriedly told of the earlier experiences: all the while he
talked his mind was busy, underneath, wondering why the pilot of the
brown ship had flown over the plant, why he had appeared to lose control
when the light flared up, why he had climbed to get away.

"He's gone!" said the watchman. "Anyhow, that's clear!"

"I hate to see him get away!" Bob said, sorrowfully.

"Whyn't you chase him?"

"I?" Bob was startled by the idea.

"Sure--you! Didn't I see Lang giving you lessons, and Griff, too?"

"Yes--but, at night--and Lang has the small ship."

The watchman seemed to have caught the excitement of a chase.

"Look here, though!" he cried, beckoning as he ran. "In the hangar is a
crate just like Griff's model--belonged to Mr. Tredway. He--he won't
need it no more. Whyn't you?----"

"At night?"

"Sure! Once you get off the ground, the air's all the same, day or
night, ain't it?"

Not exactly, Bob demurred, There were many considerations to be thought
out, but his father had said "locate the brown ship."

Here it was, flying away!

It seemed to be "up to him."

"Can we get the crate out? Can we get it started? Is there any fuel
aboard?"

Already the watchman had hold of the tail assembly of a trim, slender,
dark fuselage.

"Grab on!" answered the watchman, jockeying the fuselage so that a
wingtip missed the span of the cabin 'plane's spreading airfoils. "Grab
on! I know you lads is detectiffs, and here's your chance for a medal or
somethin'."

Bob "grabbed on!" with spirit. He had caught the enthusiasm of the older
person. It took them only a short time to jockey the craft into the
open, to get its gauges checked, to see that it had oil and at least a
tank of gas three-quarters full.

"Holler out!" The watchman stood by the "prop."

"Ready!"

"Gas on?"

"Gas on!"

"Switch off?"

"Switch off!"

The watchman spun the propeller.

"Contact!" he yelled, stepping swiftly beyond the range of those deadly
sharp blade tips.

There came the snap and bark of the motor. Cold! But Bob, feeling that
for all the precious seconds it must waste, he ought to be safe before
he might be sorry, allowed it to warm up, checked his instruments as he
had observed Lang and Griff do, and then, as the watchman, obeying his
signal, kicked away the chocks so the wheels could move forward, the
amateur pilot, steady and cool all at once, glanced at the windsock, saw
that he could take off straight down the short field, pulled open the
throttle, tipped the "flippers" so the tail ceased to drag, as the
propeller blast caught the elevators, and began to race down the field.

As he went he tipped the elevators sharply, felt the ship sway a trifle,
realized he was off the ground and moving steadily, climbing to the roar
of the engine!

He smiled a little. He had not forgotten to hold the ship level for the
brief seconds that it needed to assume flying speed after the first hop
from earth. He had not climbed her at too steep an angle, there was no
indication, at least to his inexperienced hand, of any logginess of the
controls presaging a stall. He was away!

"Now," he thought, with a sharp glance around the sky spaces, "I am in
for it. If nothing goes wrong with the machinery or the prop I guess I
can keep this crate level and get somewhere."

But where?

In those precious moments the brown ship could have gone ten miles.

"He was mightily interested in the aircraft plant," Bob reflected,
letting the ship "fly herself," as most well balanced aircraft will do
in steady air, as long as flying speed is held. "Now all that we have
found out, so far, has centered about the aircraft plant and--and The
Windsock! Could he be around there? Or----"

As a new thought struck him he gripped the stick a tiny bit tighter.

"--Or, maybe he's brought the brown ship back for some new stunt! It
might be hidden in that field again!"

He pushed the stick a trifle to the side, thus operating the ailerons,
while he used his rudder experimentally, meaning to swing in a circle.

Whether a good Providence watches over amateurs, in sports or in
professions, or whether Bob had actually learned from his lessons, the
fact is that he did not overbank or use too much rudder, and neither
felt the wind of a skid on one cheek nor the breeze of a slip on the
other. Around went the ship, in a wide swing.

Bob kept his eyes on the sky, with momentary glances at the instruments,
not all of which were understandable to him yet; however, he knew the
altimeter, the tachometer which records engine speed, the gas and oil
pressure gauges and such important ones.

They seemed all to record satisfactorily. His altitude was six hundred
feet; a little low for safety, so he climbed to twice that. The
revolutions were even and plenty for his need, as he watched the
fluctuations of the tachometer when he eased the throttle forward in his
climb, or backed it gently in the level-off.

Gas and oil recorded without a hitch or a diminution of supply.

But where was his quarry?

Far ahead Bob saw a tiny flare of red in the sky.

He nearly lost control in his excitement, but with the true air-sense he
caught the tendency of the sideslip by opposite rudder and aileron and
then banked and circled till his nose pointed straight for the dying
flare.

Someone in the sky was signaling for something!

"I'll get there soon! And see!" Bob told himself. He held the ship
level, glancing at the "bubble" in the spirit level, as he gave the gun,
opening the throttle steadily.

To the roar of the engine, the sing of cool wind in taut wires, the
sting of pulsing blood pounding a thrill-song in his temples, Bob took
up his quest, and soon saw, ahead, the dim outline of a circling ship.
It was dark. Was it brown?

He dared not get too close. Rather, he preferred to climb, so as to be
safely out of the other fellow's way if he maneuvered.

From above Bob planned to light a white flare, by whose light he could
identify the ship.

But the other fellow saw him too!

Bob needed no flare to tell him that he had discovered the brown
craft--its action was indication enough! The pilot dived, and then went
into a barrel-roll, dangerous at a low altitude, Bob thought.

The "stunt" enabled the ship to get to one side and out of his line of
flight if he dived for it.

Clearly this showed that the unseen pilot feared to be attacked, driven
down.

But Bob had no such intention, he merely followed as the small, brown
craft, speedy and capable, went fleetly through the night.

Bob, easing his throttle a little more open, as he got the line of
flight, held his elevation and his level position; he did not try to
overtake the other, he wanted to see where he went--nothing more!

So the flight held, one about five hundred feet up, the other easily as
high again. The speed was almost identical, the ships were well matched.

But the other man had some tricks up his wings, in a way of speaking!

He began to climb. Bob, fearing to be over-reached, climbed also.
Higher, higher they both went, Bob still atop the other, for he had as
much power, as well angled wings, as clever a ship as his adversary.

But the battle of elevation was short. At fifteen hundred feet the brown
'plane went into a wingover, and to Bob's dismay it was, by that
maneuver, in a reverse direction to the flight of his own, and he dared
do no maneuvering, no stunting, at night and alone!

Before he could swing in the easy circle which his inexperience
compelled him to use, the other pilot was almost out of sight. He
climbed, and thus Bob gained, but he saw that his pursuit was futile.

The man was climbing into a cloud!

In its misty vastness, surrounding a ship like a fog, an inexpert pilot
could not know, without continually watching his spirit level and other
instruments, if he flew level or on his back, if he was going sidewise
or straight toward earth. To watch the instruments "to fly by the
dashboard" was useless; he could not see to follow if he risked the
feat.

Disgusted, disappointed, he cut the gun and slowed his ship, and flew
around toward The Windsock. Somebody on the ground was burning several
land flares, he saw.

It told him one thing! The other fellow had been expected! His signal
had been seen.

For an instant Bob was tempted to try a landing, to see if they would be
startled, those people down there in the glare. Did they perhaps think
he flew the craft they expected? It would be worth something to discover
that. Or--would it? The danger, the risk, was considerable. It was
strange territory to him. The people, seeing his craft markings, its
different color, might extinguish the flares, leaving him, low, to "set
down hot" or to climb, too late, and land in trees!

No, it was not worth the risk.

If his adversary had gotten away that was the end of the adventure.

Only--it wasn't.




                              CHAPTER XXIV
                               SUSPENSE!


When Al and Curt, riding easily, reached the region of the Rocky Lake
Park, they hid their wheels in the well remembered field, preferring to
advance on foot, to spy out conditions before arriving at the roadhouse
to which they were going.

"There's something going on, over there," said Curt, as they walked,
facing traffic, along the familiar highway.

"The new dance floor--The Hangar--is opening tonight."

"That will make it easy for us to get in."

"They may not allow juniors on the floor."

"But they won't chase people away! It would be bad for the business!"
chuckled Curt. "Every young man can have--must have--at least two in his
family, and they might be dancing papa and mama."

"We can go on and see."

They did.

The new dance floor, built in an old-looking, metal-covered addition at
the side of the main hotel, was crowded. A "jazzy" orchestra, with many
toots of its saxophones, howls from clarinets, trills and staccato yaps
from its trumpet, put rhythm into the march of many feet.

"Makes me wish I had a girl and had her here and knew how to dance,"
laughed Curt.

"What I wish more is--" Al did not get time to express his desire to
have Bob along, to advise him in his rather impulsive acts. A man in a
dress suit, as the drums rolled in warning to attract attention,
advanced to the edge of the band platform and addressed the dancers
applauding their last "number."

"Lay--deeze--an'--gemp--mum!" Al nudged Curt and whispered that the man
was Jenks. "For this opening night the manage--munt has went to the
special expense--youse mus' excuse my poor way of speakin'. 'I'm only a
simple flyer, an' my eddication don't go no higher'----"

Al exclaimed, and Curt scowled at the aspersion thus put on the
intelligence of the most manly, most steady, best educated general class
of men in industry--pilots!--but they listened, nevertheless.

"The manage--munt has put on a extra fine show for tonight. In fact,
folks," his manner became more natural, "we've engaged a stunt flyer to
come over here tonight, to fly around up in the dark blue, and to do
stunts, with rockets and colored lights so you can see what he does. I
understand the whole crate is to be lit up some way. So, if you'll all
step outside, while we put tables in here for refreshments, you will
have the free entertainment as soon as we can get his signal and let him
know to go ahead."

As Curt and Al were already outside, they craned their necks.

While the laughing couples gathered, a small, red flare was visible. The
men who seemed to be awaiting this signal, lighted flares. But to their
amazement the ship did no stunts! It went away!

"Funny!" muttered the excited, disgruntled manager, Jenks, close by Al
and Curt.

As the flares brightened it seemed as though there were two airplanes
dimly reflecting the light.

"But they aren't doing any stunts!" complained a girl to her partner.
"Wait!" he counseled. Waiting, however, did no good.

The dancers, murmuring, and the manager, trying to apologize, saying it
must not be the right crate, went back to dance, shoving the refreshment
tables roughly aside.

Al and Curt, waiting, watching, wondering, saw the men stick the stubs
of their flares into the ground and walk off.

"Look! He's coming back!" Al pointed to a speck. They listened and heard
the drone of an engine.

"He's back again!" shouted Al, and the people came out again, standing
with backs to the glaring light, shaded eyes turned upward.

"No--he's flying low, though," commented Curt.

"Yes, he is."

"Look!" Curt caught Al's arm. "He's in trouble--isn't he?--yes, he is!
Listen! His engine has stopped--dead!"

"Yes, he's gliding!"

"He can't land here," said Curt. "He's too low to spiral and shoot this
little clearing--anyhow, it isn't a place to land--not for night
landing!"

"I wonder if the same things are happening that happened--when Mr.
Tredway was--lost!" Al murmured. "That time, we heard the engine, and
then the ship dived."

"This one isn't diving--it's gliding!"

"I know, Curt--he's getting over Rocky Lake. Come on!"

"There he does go--down!"

Off they pelted toward the road.

An airplane had been cruising over the flares. Its motor had stopped.
That was sure.

And no one knew it better than Bob.

For he was the pilot whose engine stop had left him with a "dead stick."
He must glide. He had enough gliding angle, he supposed, to take him
back to that providential field--if he could throw over a flare and make
some sort of a set-down!----

It was dangerous--but it must be done.

For, in spite of its danger, knowing well what might happen, Bob had
shut off his own engine--deliberately!

He had to--to save his life!

"Look!" gasped Curt, running. "See that glare? The 'plane----"

"On fire!" panted Al.

Appearances are deceiving. To Al and Curt, on the ground, with darkness,
distance and trees to screen the truth from them, it seemed as though
the glare they saw beyond the grove must spell a blazing airplane.

Instead, the light came from a landing flare, dropped by Bob.

As he headed over The Windsock roadhouse, and decided to give up, to
return to the aircraft field, he had all of his mind and attention on
his craft. Because of that he was able to notice a mystifying, if tiny
bluish light, intermittent and flickering, close to the pipe that
conveyed fuel from the tank to the mixing carburetor.

"That's an electric spark!" he decided. He was right.

Somehow, either through one of those malicious acts which had already
been done to other ships, or from a rubbing wire, some electrical
conducting wire had worn off its insulation and was bare, and each time
it rubbed or touched metal it made a spark.

If there is one thing more dangerous than another in the air it is the
menace of an open spark close to gasoline feed lines and carburetor
mixing chambers.

Knowing it well, unable to determine the cause, but sure that the spark
was electrical and dangerous, Bob took the only safe course. As Curt and
Al had observed, his engine stopped. He cut off the ignition.

The sparking light ceased.

"Now," thought Bob, "I daren't use my motor. That means I must glide. At
this height, if I remember what Lang said, the angle that will give me
safe flying speed will about take me to that little field we first saw
the brown 'plane hidden in. Can I make it?"

He depressed the nose, watching, by his sense of touch, how the stick
and rudder bar acted. As he moved through the air he elevated the nose a
trifle, to get as flat a gliding angle as he dared; but his whole mind
was concentrated on that feeling, that sense of heaviness in the
reacting of the controls. When they began to respond sluggishly he knew
enough to sense that he was losing flying speed, approaching the danger
point called stalling, in which the ship gets out of control, drops or
slips or does some other uncontrollable maneuver.

Always, in time, he lowered the nose, picked up the needful speed, and
thus, by coming as close to the "graveyard" glide, or flat angle, as he
dared, and yet conserving enough reserve speed to keep the lift of the
wings more sustaining than the downward pull of gravity, he held his
craft in the air.

Always the nose, pointed into the wind, went lower. Always, as he tried
to penetrate the darkness of the night and of the brown earth below, his
eyes, over the cockpit cowling, searched for the flattish, light spot he
wanted. Along its inner side was the strip of turf he needed.

Fear-thoughts flashed through his mind:

"Can I glide that far? Will I overshoot or undershoot? Will I misjudge
the height as I come down, if I do make it? Will I set the ship down too
suddenly, so it will bounce off and then--with too little margin of
height to get speed again--crack up? Will I stall too high and smash
down? Will I be going too fast, and run too far? Can I glide in to the
turf or will I set down in stubble and nose over?"

Resolutely, by all the will power he had, Bob crushed out those
nerve-deadening, muscle-binding terrors.

There was the field. Where, now, did they keep the light producing
flares? Oh, yes! There, in that little boxlike compartment.

He flung a detonating flare that would light in the air or on striking
earth. Its light was what horrified Curt and Al.

To Bob, its glare was a great relief!

The white gleam showed, far ahead, faintly lit, the field. His course
would take him toward it, but he altered the direction of his flight
slightly to get over the turf, then corrected the bank, leveled his
wings, depressed the nose still more, picked up speed and, with all his
force, sent a landing flare into the air, as far ahead and to the side
as he could fling it.

Then he "shot" the field, got his nose directly onto a line with the
large trees at the end of the field, pulled up the nose more, to kill
all the forward momentum he dared, and then----

Bob gasped. He was too far to one side. He would land in the stubble.
Also, he was a little too high.

Wildly he flung the flare he had been getting ready.

Then, from some hidden source of remembered instructions he got the
instinctive knowledge of what to do.

He dropped the left wingtip by pushing the stick sidewise, and felt the
ship tilt. It went into a sideslip. That both lost speed forward and got
him further over to the left.

Opposite rudder, hard! Up left wingtip, down right! Nose down a little!
Speed enough to go on!

With his heart in his mouth, looking swiftly down, Bob saw the earth
seem to come up at him. Up elevators! Stall. He'd have to take it! He
was close to earth, over turf. He must not keep that nose down and glide
into the trees or taxi beyond the end of the turf.

The ship stalled, landed with quite a jar--but the trucks held up!

And Bob, from his heart, breathed a little prayer of thanksgiving.

He had done his best, had held his head, and--he was safe!




                              CHAPTER XXV
                             CROSSED WIRES


By the time Curt and Al got their bicycles and pedaled to the vicinity
of Rocky Lake, Bob's flare was out and they had no means of ending their
suspense until they had looked around in the picnic grove and assured
themselves that there was no burning airplane in sight.

They rode along the highway.

"Isn't that a flashlight, in the old field?"

"It looks like one, Al."

"It is!"

They pedaled faster. Presently the pair reached the field; soon Bob,
using a small pocket flashlamp, was telling his brother and his best
friend how the electric spark had worried him.

"I knew the brown airplane was gone," he continued his explanation, "the
only thing left for me to do was to head back to the plant. But I saw
that quick little flicker close to the gas line and cut off the ignition
switch."

"What are you doing now?"

"Tracing the wiring," Bob told his brother. "And here is a wire! It
ought not to be run so close to the gas line! And here is another, away
back under the dash instrument board. They cross!"

"Crossed wires!" gasped Curt. "That isn't right!"

"Certainly not!" agreed Bob. "We've learned enough about airplane
construction at the Tredway plant to know they don't do such careless
things as that!"

"Then somebody deliberately did it," concluded Al. "It's part of the
scheme to damage the crates."

"It's worse than that!" Bob climbed to the ground and faced his
companions. His face, hard to see in the dark, because he was saving his
electric battery, was very serious. "It's worse than just tampering!
Fellows--this is Mr. Tredway's own airplane!----"

"I see," commented Curt soberly. "Some one wanted harm to come to the
owner of the plant."

"And the 'some one' made sure it would. In daylight," Bob stated, "that
spark wouldn't be noticed. It was only by being out in the dark of
night, that I could see it."

"But crossed wires ought not to rub enough to wear out the insulation in
a short time," objected Al.

"Neither they did. Al--Curt--the insulation was scraped away!"

They were silent for a long moment. The full wickedness of that
deliberate act made each of the youths feel rather cold. They were
dealing with something more sinister than an attempt to make away with
small airplane supplies, to damage airplanes for the purpose of injuring
the reputation of the manufacturers, as they had decided the conditions
seemed to indicate.

"Well," Curt became practical, "you can't fly that ship home, not in
that condition."

"If we had some adhesive tape," Bob said, "I could tape the wires and
get back to the aircraft field."

"I've got bicycle friction tape in my little toolcase." Al ran to get
it.

"The place is hard to reach," Bob told Curt.

"Maybe I could do it," Curt responded. "My hands are thinner and my
fingers are longer than yours."

As soon as Al brought the roll of pitched fabric, Curt, with the
flashlamp set for steady burning, located the damaged insulation and
began to work with strips of the tape, having some difficulty in winding
it without pulling the wires too much.

"This is going to be a slow job," he called out. "Bob, somebody ought to
go and call up Griff, to see if he has any news."

"I think so too," Al agreed.

"Why don't you both go!" Curt urged. "One could stay at The Windsock and
watch and the other could come back with news--or, Bob, you could ride
back on my wheel, to The Windsock with Al, and then come on back here
and we two could fly back to the hangars together."

"Would you trust yourself with me, in the dark, flying this ship?" asked
Bob. "Something else may be wrong with it."

"That's so. I'll look it over. I know how they inspect them," Curt
suggested.

Al and Bob agreed, and went to the two bicycles. Off they rode.

"There's that 'plane again!" Al pointed to a tiny red flare high up over
the roadhouse ground. "He has come back."

"I suppose I frightened him away," Bob said. "He probably thinks whoever
chased him has given up, and he has come back."

"One thing bothers me," Al observed, forgetting his weary legs in the
fresh excitement. "Why would a crate that has a pilot who flies away
from pursuit come back to do stunts?"

"I can't answer that," Bob replied. "Let's get there. See! He is
looping, and he has lighted some sort of rocket or bomb that makes a
trail of fire to show his stunt off in the dark."

"It's pretty, isn't it?"

Bob agreed with his brother's exclamation as the airplane, high above
them, with fireworks leaving a comet's tail behind it, made a series of
loops, dived, zoomed, made a sort of "S" of fire by side-slipping first
one way and then the other.

When they got back to the roadhouse the display was over. Ground flares
were going and it was clear that the pilot meant to land.

"We're going to see who it is, after all," declared Bob, thrilled by the
possible revelation that was to come.

Curt saw the gyrating ship and its glowing trail of sparks. He watched
for a moment and then went doggedly back to his work. If Bob needed this
sport craft, Curt proposed to have it ready if careful, methodical work
could get it so.

Surprised, he heard himself addressed by a youth who came over from the
farmhouse whose builder owned the field.

"What's goin' on?" asked the farmer's son.

"Some display for the opening of the roadhouse dance floor," Curt
replied, tightening down the tape and clipping off the end with his
pocket knife.

"I don't mean yonder. I mean here."

"Oh! A little trouble. Crossed wires."

The youth did not understand; but he accepted the explanation.

"Ain't you awful young to be a aviation flyer?" he asked.

"I don't--I'm not the pilot," Curt stated. He explained. Then, his task
finished, he clambered down to see the glow of the distant, concealed
ground flares, and to guess that the sky rider was going to land.

"This is gettin' to be a regular aviators' place," said the youth to
Curt. "Guess pa ought to put up signs, 'Places to land for rent.'"

"Do many crates land here?" Curt was surprised.

"Well--look at them tracks!"

Thus having the spot indicated, even in the dim light Curt was able to
see that deep ruts had been made, not only in the soft, ploughed edge of
the field, but also on the turf.

"Hm-m-m!" he had no explanation to comment. It was unimportant.
Something of greater concern was on his mind.

"See here, buddy," Curt said, "will you help me 'warm up' this ship?" He
was searching for two stones or blocks big enough to hold the airplane
still while the propeller revolved. "The pilot might want to take off
now that I've fixed the damage." The boy agreed. Curt, locating several
rocks near where the brown 'plane had once been hidden, set them under
the wheels, and then, realizing that the ship must take off facing into
the wind, he got the youth to help him drag the tail around, to pull the
whole ship as far up at the end of the turf as possible.

"First time I ever worked around a--er--'grate'----"

"'Crate,'" Curt corrected, smiling in the darkness. "That's a slang way
of speaking of an airplane, and it means either a term of fondness, or
of disgust, according to how the user feels about his 'ship.'"

"I see. Gee! Wisht I could be one of them aviator flyers."

"You can, if you are willing to study enough," Curt said. "It means hard
work. There's a lot to learn. But a fellow who has ambition can get to
be anything he likes."

"Not without being educated more than me."

"You can pick up some education while you're studying in 'ground
school,'" Curt explained. "After you learn the parts of the airplane,
the way each one works, what it is for, and so on, and how they are put
together, you have to study about airplane engines--the principle of the
internal combustion engine and what all the parts are for and how they
work. There has to be study of--let's see--oh, yes!--aerodynamics--how a
ship flies, and why, and what different air currents do, and how to know
their effects. There's navigation, too--the beginnings of it, anyway."

"All that? I thought you got in and pushed something and----"

"If there weren't so many people who thought that," Curt said soberly,
"we wouldn't have so many accidents. Flying is a science; and there's
more to it than getting into the air and going somewhere. It takes
ground school study to learn the foundation part, and instruction
flights to learn how things are handled, and solo flights and stunting
to show you how to handle a crate in an emergency--and navigation in its
practical applications, for long flights. But if you are in earnest, you
can get all that, and pick up practical arithmetic and grammar and so
on, in night school at the same time."

"Not without money!"

"No--unless--you might come over to the Tredway aircraft plant and I'd
introduce you to Barney--Mr. Horton, the manager. He might give you a
chance to work as a 'grease monkey' in the field, for he is awfully
nice. He helped all of us."

The youth agreed eagerly, and then, with the chocks set and the ignition
switch off, Curt told him how to work the propeller around, and got him
back to safety as the ignition switch followed the gas "on."

The engine took up its roar, and Curt knew enough to shut down the
throttle to idling speed, allowing the slow revolutions to warm up the
power plant. He knew little about oil pressure and instrument readings,
but he knew that an engine, to function safely and steadily, in flight,
must be warm.

While he busied himself getting everything as nearly ready as his
ability allowed, Bob and Al reached the roadhouse.

The airplane had already "set down."

"It's the brown one, and no mistake!" Al was thrilled.

"Yes," said Bob. "Now, Al, the pilot must have gone inside the
roadhouse. I don't see him around the dance place. You could go in to
ask for his autograph. I see you still carry that little book. It ought
to be easy to get a look at him, have him pointed out to you. That's
really all we need."

Al agreed. He had no difficulty in getting a busy waiter to jerk a thumb
toward one of the private compartments.

Al went to its door, pushed aside the curtains--and stepped back.

What he saw stunned him!




                              CHAPTER XXVI
                     THE SKY SQUAD GOES INTO ACTION


Three men faced one another in the small compartment, made to look like
a passenger 'plane cabin.

As Al, at the curtained entrance, recognized the one facing him, all
three turned to look.

With a mumbled apology Al backed out.

More than anything else, he wanted to get away, to see Bob!

The man who had faced him was Mr. Parsons, partner in the aircraft
plant.

The man to his right was the mysterious stranger whom Al had seen in the
supply room!

The third man----

Before Al could form his mental picture of a face that seemed familiar,
a bus-boy, with a heavy tray of soiled dishes, bumped against him.

"Get out o' the way," the youth grunted, to Al, and gave him an angry
push with his free hand. Al, his balance disturbed, stumbled
forward--into the arms of Mr. Parsons at the door.

Struggling, squirming to get out of the powerful grip on his arm and
shoulder, Al found himself held as if in a vise.

Suddenly his whole body went limp. His head dropped, his eyes closed. He
sagged down, and surprised and disconcerted, imagining that the youth he
held might have fainted in his fright, the man released him, lowered him
to the floor while he looked up, intending to call for aid.

Behind him another face looked out, the bearded face of the man Al had
seen previously in the supply room.

"What's up?" asked the latter.

"I am!" cried Al, shrilly, as he tensed his muscles, swung free of Mr.
Parsons as the latter bent over him. Like the leashed spring of a
panther Al's squirming, swift move took him out of danger.

To cries, to shouts of surprise and of inquiry, Al eluded the grasping
hands of a waiter, dodged a diner's gripping fingers, evaded the move of
a man to block him at the door, and was free!

Quick thinking and a ruse had prevailed where strength was not enough to
accomplish his wish.

Speeding along, outside, after vaulting the veranda railing, Al quickly
located Bob. With a wave of his hand Al signaled. His progress was swift
as he scampered across the parking space, between standing automobiles,
toward an old barnlike structure backed into the grove. Bob, seeing the
wave and Al's progress, dodged, on his own part, among the cars until he
rejoined Al in the open door of the old, dilapidated barn.

"What happened?"

Al, pulling his brother back out of sight, recovered his breath.

"I bumped into Mr. Parsons----"

"No!"

"Yes--and the man we saw in the supply room----"

"Well! What happened then?"

"There was somebody else with them. And--I didn't recognize him, because
I was so surprised and excited--but his face 'rang a bell' and I'll
think who he was when I get quieted down."

"What made you run?"

Al explained.

"Yes, and there comes Mr. Parsons! He's looking for me," he ended.

"He has something in his hand--a package----"

"Listen!" Al drew Bob further into the dark interior. "Bob--when I
blundered in on them, those men had--what do you suppose?--the company
books!" Al clutched Bob's arm tighter. "You remember, we hid when Mr.
Parsons was in the offices--he took those books!"

"Yes," Bob's whisper agreed. "Now he's been showing them to that man we
saw, and to somebody else."

"Mr. Parsons isn't as honest as Griff wanted us to believe."

Bob shook Al's arm reassuringly. "No," he admitted, "I thought Griff's
story was part of--what did they say in the war?--oh, yes! It was
'camouflage.' Fancy paint to conceal something."

"If we could only get the books away from them--and tell Barney!"

"They may be coming to look for you. Mr. Parsons must have recognized
you, Al. I wonder if there's a haymow over this old floor?"

"You go along one wall and I'll take the other. We'll see!"

They hurried away from one another. Presently Bob called out softly and,
following the wall, with one hand touching to hold his place, the other
extended ahead to avoid bumping into any obstruction, the youngest of
the Sky Squad found his way to Bob.

There was a ladder against the wall. Bob whispered instructions and
started up the dark, uncertain ladder. Bob had hardly reached the top
and called down a low reassurance when Al almost scrambled in his
eagerness to get up quickly.

Voices were growing louder. Some one was coming! It must be Mr. Parsons.

At the top of the ladder, Al fell softly onto the upper floor boards,
and he, with his brother, bent attentive, strained ears to catch the low
murmur from below.

"He's from the plant," a voice called, and Bob recognized the quick,
sharp tones of Mr. Parsons. "He was a boy from the plant."

"You got those books wrapped in record time!" someone else chuckled.
Then, as the youths drew their heads back, turtle fashion, to avoid the
glare, a match was struck.

"Nobody here--but yonder's a ladder."

"Better go up and have a look," said a third, deeper voice. "We can't
afford to have those kids snooping. I think Barney brought them into the
thing. They're only kids--but they have eyes!"

Bob, with a twist of his neck, looked around in the dim upper room. Its
end window, dirty and cobwebby, allowed the moonlight to stream in. The
shaft of dull light streamed across, slantwise. Bob, following its path
with his eyes, touched Al's arm. Gently he directed his brother's gaze
toward a corner.

Sacks, used for packing corn or other cereals, were piled up there.

By common consent the two began a slow, cautious movement toward the
sacks; but Bob, quick in an emergency, drew the whole pile, very
cautiously, partly lifting the lower ones, to a darker place.

Al, close beside him, divined his idea. They could hide under the large
cluster of heavy burlap bags.

By the time that a match was struck in the upper floor they were lying,
crouched, under a number of the burlap bags.

"Not here! Guess the kid was scared and ran away."

"Wait, though." Bob's breath almost stopped. Had the other man who came
up discovered the sacking?

"Wait, though," the man repeated. "We meant to compare the books
tonight; that's why I took all the trouble with those stunts, to have a
logical excuse for landing here. We can't, now! Those kids may have
telephoned somebody--whoever they're working for. Suppose we hide the
books, and get together tomorrow night. I'll take the crate back and
come over by train."

"Good way."

In their stuffy concealment the brothers heard steps, low muttered
suggestions. Evidently a place to sequester the company records was
selected. The youths quivered and Al nearly screamed aloud as a sack was
dragged from the top of the pile. But the sack did not pull off the ones
they clung to over their perspiring heads.

"That's the stuff! On that shelf, and cover 'em up. Nobody would think
of that place."

"Won't Barney miss them?"

"Let him worry a little. It will do him good!"

The voices receded. The heavy tread ceased. Scuffling sounds told the
brothers that the men had descended the ladder.

"Well," whispered Al, "we're safe----"

"And we can take the books back----"

"Can we find them?"

"They said 'on the shelf.' Feel around, as soon as they are out--wait!
Al, I'll slip over and spy out through the window----"

Al sat on the floor, among the sacks, mopping his brow which was wet
with hot perspiration that had, a moment before, been ice cold. Bob
waved across the bar of moonlight. The trio of seeming conspirators was
safely away, he indicated.

Again using their hands, they felt along the walls.

With his head, though jarred only slightly, Bob found the shelf. A quick
exploration defined the books, in a compact roll of tape-tied cloth,
hidden under the sack. It was a second's work to remove them and to
rejoin Al.

"Now--how can we get them away? Won't they be watching?"

"Let's go down and see."

Alertly, and with caution, Bob protruded his head over the edge of the
opening by the ladder. He was fortunate! In the doorway stood the
unrecognized member of the party, smoking. Evidently he had returned.

Bob watched, holding Al in check by his grip on the younger one's arm.
The man did not propose to leave, it appeared.

The sound of an airplane motor starting conveyed the truth. He was
waiting until his ship was ready before going into the open.

Bob waited, Al at his side. Neither moved more than was absolutely
essential.

But Al, try as he would, could not suppress the horrible inclination to
sneeze, induced by the dust in his nostrils from the dirty burlap.

"Huh--sh--huh--sh!" he tried to hold back, but Nature got the better of
his will.

"Huh--shoosh!"

"Now you've done it!"

"Couldn't help it--look--the window will open. You could drop!"

The sound of the man ascending the ladder came clearly.

Like two swift gazelles the youths dashed across to the window, wide and
old. It was part of the door through which hay was drawn up, they
discovered. They tugged at it. On rollers, but stiff from disuse, it
stuck. Panting they struggled. Closer came the ascending steps, a call
to know who was "up there!"

The window slid open a foot--another foot.

"I'll have to drop," said Bob. "You get back and hide again."

"Too late! I'll drop the books to you! Go on--quick!"

Bob hung by his hands, gave a swift glance down, let go! No sooner did
he land, with loosened muscles to avoid the shock as much as he could,
than the package of heavy books landed beside him.

Swiftly he grasped the package, and ran.

Al, almost caught, doubled with a swift, bending squirm, as the angry
man reached to grapple with him in the moonlit doorway. By his quickness
Al was able to get away for an instant.

He tried the same ruse he had used so well before, but in another form.
Every ounce of weight he could put into it he gave to a run away from
the ladder. Then, doubling on himself, but tiptoeing and bending as low
as he could, avoiding the moon ray, Al crept softly along. The man,
following the direction of the footfalls, and thus trying to locate his
quarry in the dark, did not see the silent, gloom-hidden form slip along
the wall. Al was down the ladder before his ruse was detected.

But the man ran to the doorway, shouting through its opening.

Bob, racing toward the bicycles, realized that the other two men,
catching the warning shout, were bearing down on him. Like a rabbit he
reversed his route, slipping in among the trees behind the barn. But Mr.
Parsons and the other mysterious stranger were determined men. Bob could
not run and be silent. He dared not creep. They were too close behind
him.

Al, seeing that this pursuit was close, tried to divert attention by
shouting as he ran, openly, across toward the bicycles.

But this did not draw the others away; they felt that Bob had a parcel
for which they meant to catch him. On and on, through the grove,
dodging, squirming past trees, through briers, Bob went.

Curt, at the field, with the engine idling on the airplane, did not hear
the pursuit until Bob, almost worn out, nearly done, came racing along.
Then, seeing him, Curt ran to meet him. From the grove behind came the
crash and shout of pursuers.

"The books--hide!--" Bob could say no more.

Curt caught the package as Bob hurled it. Then, with an instinct that
amounted to genius, Bob noted a flattish stone, and as he ran he bent,
pausing an instant, and came up tugging along the small, flattish
boulder that, in the dark could be mistaken for the package of books.
Unconcernedly, as though watching in the role of a spectator, standing
on the parcel of books, Curt remained quiet, and the men raced past him.

From the road, where he flung his bicycle, knowing well where Bob would
head for, Al arrived. He raced toward the airplane just as Bob ran in
the same direction with his boulder.

Al, not unnerved by his excitement, realized that if the propeller was
turning, some chocks or other means of holding back the ship were in
place. He bent under the wheels as Bob arrived.

"Get in!" he cried. Bob, pretending to drop the books in, let the
boulder fall beside the turf. While he was climbing in, the men paused
for an instant by Curt who said, sharply, "There he goes!"

They turned, saw Bob was making for the airplane, and ran toward him.

Al tumbled into the rear cockpit, determined not to be caught after the
enmity he had awakened.

"Take me!" he cried, but the roar of the engine drowned his voice as
Bob, risking everything, in the dark, opened the throttle.

Up went the elevators enough to lift the tail as the propeller stream
swept against them.

Along the turf the ship began to move. The men, aware of the sinister
menace of the whirling blades, fell aside. Bob, sensing the near
approach of the end of his runway, lifted the elevators again, felt the
ship going light, gave her the gun, holding her just long enough on the
level after the take-off to get his speed--then up he roared.

And a boulder beside the turf remained, while Curt, with the books under
his arm, among the trees, went to Al's bicycle--and delivered the books
to his uncle's study.

But he didn't stay at home. Mr. Wright was not there. Bob and Al would
fly to the plant. Thence, on tired feet, Curt pedaled.




                             CHAPTER XXVII
                              DRIVEN DOWN


Almost as soon as he lifted the airplane above the grove beyond that
cornfield, Bob recovered his wind and his confidence.

Al, of a more nervous type, was still trembling in his after-cockpit
seat, but his excitement was changing from that of the recent adventures
to the thrill of sky-riding at night with his brother. There was not
only the elation of the climb to keep his nerves quivering; also there
was the uncertainty of what might happen because of Bob's lack of skill
and experience.

Climbing steadily until he was over five hundred feet above the earth,
Bob felt none of his brother's uneasiness or excitement. He was
confident that he could control the airplane as far as straight flying
was concerned; his only difficulty would be the landing, not the easiest
thing for a skilful pilot unless a signal could be given that would make
the plant watchman illuminate the small field.

Bob, making a long swing, banked gently, to head back for the plant,
calmly considered the elements of the situation and tried to plan, as
well as he could, how to meet whatever came up.

Al, giving more attention to sky and earth, as they straightened their
course, correctly pointed for the field at the plant, saw a tiny set of
glinting lights far away in the sky.

Impulsively he caught the stick of the dual control to waggle it. That
was the only way to attract Bob's attention; but Al, in his quick way,
shook the stick and then held it pretty far to one side, and Bob, not
expecting the move and unaware at first that Al did it, felt his heart
sink for an instant, fearing that something had gone wrong with the
controls.

Al, horrified at the effect of his move, sat, tensely still, waiting for
a crash. Bob, alert, decided in a flash that he would do all he could to
avert the smash before he gave up hope. He made the necessary moves to
correct the slip.

To his delight the craft obeyed promptly, coming back into its proper
position quickly. Turning to reassure Al, Bob saw his brother violently
gesturing toward the sky to one side. As he looked Bob saw tiny lights
and knew them for the flying lights of a craft.

The explanation came at once. Al had attracted his attention to the
airplane knowing it must be the brown 'plane. Probably the two men who
had chased Bob had contrived to tell the pilot, before he took off,
that--as they supposed--the company books were in Bob's possession. With
a wave of his hand toward Al, reassuring him, Bob set his course for the
flying place belonging to the Tredway plant. He was being pursued by the
ship he had, recently, followed; it suited him. He would lead the ship
back there, contrive some way to attract attention, get Al to drop
flares, and then, landing, telephone all the airports nearby to identify
and stop the pilot who must eventually alight for fuel.

The pursuer, however had no intention of being lured.

Bob realized it, at the same time that he recalled how swiftly the other
pilot had climbed to escape identification earlier at the plant.

Instead, the brown ship had some sinister intent toward himself, Bob
guessed, for it was climbing rapidly, and Bob, unaware of the safe
climbing angle or stalling angle of his own craft, dared not risk so
steep a tilt.

Higher, always higher above him, went the other man's lights.

The wing over him obscured Bob's view.

He turned to Al. The younger brother leaned out and stared.

"Going up yet!" he cried, and gestured.

Climbing! Climbing faster!

Bob opened his throttle steadily to the full capacity of the engine.

He proposed to gain all he could in speed, and that meant distance ahead
of the other, while that other airplane climbed. He knew he could fly
faster, on the level, than a climbing ship could, and he saw the other
lights slowly becoming somewhat fainter, smaller.

But that did not last long.

In a few seconds the other ship leveled off and began to approach. Bob,
craning his neck to get a sight of the other craft beyond his own wing
spread, saw that the other man, evidently angling down and pointing
directly for a position above him, meant to overtake him and was quite
capable of doing it. He had superior experience and skill.

Bob realized quickly that the better part of valor in an airplane at
night, under such conditions, was to give up.

"Or, at least to pretend to give up," he reflected.

To carry out that pretence he reached into the signal light stores and
selected a light. This he tossed back to Al.

His signal and his act were understood.

Al knew that Bob wanted light. He ignited the flare, which proved to be
a green signal blaze, flung it overside and watched its tiny parachute
catch the air and suspend it.

In that light he swung his eyes to see what Bob meant to do.

The other pilot, arresting his dive, also flew along level, and watched,
it appeared.

Bob, lighted by the glowing green flare, pointed to himself and then
pointed to earth.

The other ship, coming steadily closer, was quite plain in the
illuminated space. Its pilot made a similar gesture, pointing first
toward the airplane Bob piloted, then downward.

Bob lowered the nose and began to spiral, as though looking for a spot
on which he might safely "set down."

On a wider swing the other pilot flew, observing his act.

Swiftly Bob summed up the situation. Beneath him, easily reached, was
the wide ribbon of the asphalt highway. By heading almost directly into
the wind he could "shoot" the road, and by keeping his engine running at
partial speed he could make a "power stall," letting the craft settle
very gradually instead of trying to glide down, guess at the correct
height and then stall and drop. To do the latter in the comparative
darkness of the highway might result in smashed landing gear or worse if
he stalled too high and dropped, or it might happen that he would "put
her on hot," or at too great speed and without stalling, come against
the ground. In one case out of ten that might enable him to roll along,
but if he struck the slightest uneven bit of road, or a bulge of the tar
at the intersections of the asphalt road blocks, up would bound the
ship, perhaps to stall herself and crash.

By using power he could keep flying speed while gradually settling until
his wheels contacted the road. He could also rise more readily if he
discovered that he had gone too far to either side of the narrow
road--wide enough in fact but narrow from the standpoint of its use as a
landing place.

He gave up the half-formed notion of trying to outwit the pilot.

The man meant "business" and that might spell trouble for an amateur.
Better far would it be to set down and see what came of it.

As he saw the roadway ribboned out straight ahead, with no headlights
observable in either direction, Bob lifted the nose a trifle, adjusted
the throttle until, with the road streaming backward under him, he saw
it very gradually growing wider and clearer.

Almost perfectly he landed. Being a straight road he had lots of time to
taxi, with his gun cut and his only care being to hold the ship on its
wheels and not let a wing-tip scrape the asphalt.

To his surprise the other pilot did not land.

Instead he seemed to be circling at a very low altitude, not a hundred
feet up, and with only bare flying speed, diving ten feet to catch up
his speed and then climbing back to circle again.

"We can't leave this crate standing on the highway," Al called as soon
as Bob had the engine running at idling speed. "Suppose a Sunday driver
comes along at sixty miles an hour?"

"What else can we do?" Bob swung in his seat.

"That's so. If we go up he'll ride us down, and we might not make as
good a landing--you might not, I mean."

"Yonder comes a car!"

As Bob pointed, Al leaned out and stared.

"The headlights blind me," he declared, shading his eyes with his cap
brim and hand.

"It's--it's the ones who are after us," called Bob. "See! One of them is
stopping the car and the other one is jumping out." He turned to Al.

"They think we have the books. The man in the brown ship drove us down.
Mr. Parsons, in his car, with the other man, is coming to get us."

"Well, they won't!" exclaimed Al, scrambling out of the airplane.

"No! You run into the woods to the right of the road."

Al, as soon as he was on the ground, used his heels to good purpose.
Bob, pausing only to bundle up some folds of his coat to make it look,
from a distance, as though he carried a package under it, slipped to the
road and ran the other way.

Driven down, they nevertheless left the pursuers outwitted.




                             CHAPTER XXVIII
                            CURT'S DISCOVERY


"Those books are off my mind," Curt reflected as he pedaled slowly
toward the aircraft plant, "but my legs aren't. I'd go to bed and rest
for a week if it wasn't for seeing what Griff is up to."

He had ridden only a block or two away from his uncle's residence, where
he had deposited the books, when a thought occurred to him.

"I know how to get a 'tow' to the plant," Curt whispered to himself,
swinging his handlebars to turn into the next cross street. "They
usually get shipments of fabric on the eleven o'clock freight, and our
truck is there to load it in." He glanced at his wrist watch.

"Yes," he told himself, "it ought to be loaded or nearly so--and that
means the truck will be starting soon. I'll ride along till it catches
up with me and then let it pull me where I'm going."

It was a reasonable notion and well-founded. That it was sound was soon
proved, for Curt saw the truck turning into the street just ahead, from
the direction of the station.

He had expected it to come from the street he had passed, but realized
that it must have followed the direction it had been pointed instead of
turning around in the station yards; increasing his speed for the
moment, Curt caught up with the tail boards of the large truck, took
hold with one hand, set his coaster brake, and rode in comfort, resting
his weary feet.

To his great surprise the truck turned off at a crossroad.

"What does that mean?" he wondered.

He let go and dropped back a few yards, intending to let the truck go;
but it bothered him to decide what caused the change of route.

Curt resuming his pedaling, following at a little distance, determined
that for all his weariness he ought to find out why a truck, openly
laden with cases and parcels, boxes and canvas sacks, should not go
directly to its destination to be ready for unloading when the plant
opened in the morning.

The ride was not more than a half mile.

Curt, keeping at good distance, let the truck get around a bend. He
could follow by the sound of the motor. He did not wish to be seen.

There was in him the thrill of the discoverer of a new clue.

When the motor ceased to send its roar across the distance to him Curt
laid Al's bicycle, which he had ridden from the cornfield, beside the
rutted country road and walked, screening himself carefully, to the
bend.

"No truck should stop in this out-of-the-way place," he decided. "I'd
better be careful. They might have a guard set at the turn."

There was no guard, however. Evidently the truck driver and his
assistant had no suspicion that they were observed.

Openly the truck stood in the road, to one side. Curt, able to
distinguish its bulk, was too far away to see through the darkness what
was going on.

"Maybe a broken drive chain," he thought. "Still, I'd better be
certain."

He made a slight detour through the pines along the byroad, being
careful to make as little sound as possible, working around toward the
position of the truck. Whatever sound he made was soon drowned by the
roar of a motor.

"Just a repair," he decided. "They're going."

Instead of getting further away the motor pulsation became louder.

"That's another car coming," Curt told himself, "and it's a heavy duty
motor, too."

He made fast progress toward the edge of the trees. There, hidden behind
a large trunk of pine, he could see the dim road, the dull outline of
the truck, and the moving forms of men lifting things out and piling
them by the road.

"They're unloading the truck!" Curt was amazed. Was this some bold
banditry, some open theft?

To his further astonishment and mystification the other truck came along
and stopped. There was an exchange of low, but jovial banter between the
rough drivers and their helpers, but no allusion was made to their task.
Instead, the men on the truck just arrived began also to unload bolts,
cases, boxes, sacks, from their vehicle.

Curt could not figure the problem to a satisfactory decision. Were they
substituting one load for the other? Why?

At any rate, they would be occupied for several hours, Curt thought. He
made his way quietly back into the wood and hurried toward his bicycle.

"I'll ride to the plant, get the watchman to telephone for the police,
and round up those fellows."

Every ounce of his reserve energy Curt put into his pedals as he bumped
along the byroad and then raced down the main highway.

When he came within sight of the aircraft plant he was surprised at the
activity displayed. The flood lights were on. Far up overhead he heard
the sound of an airplane engine.

"Oh!" Curt was reassured. "It must be Bob and Al coming in. They will be
glad to hear I put the books away safely, and then we can all ride back
to the truck--no, we can't!" He recalled that his own wheel was parked
at The Windsock--if no one had taken it.

There was no one in the watchman's place by the main gate, which was
open. Curt decided that the man was at the flying field to give
assistance to the airplane as it landed.

"Hello!" Al, turning at the door of the administration offices, hailed
Curt. "Come on!"

Curt raced across the yard, joined Al and Bob at the office building
doorway.

"I thought--" he gasped, "I thought you flew!"

Rapidly Bob explained. "We hoofed it back," Al added.

"Then who is landing--or shooting the field to land?"

"Must be Mr. Parsons bringing in the ship we deserted on the road. Did
you leave that parcel of books at Dad's? Good! But why did you come back
here, Curt?"

A quick explanation set everything clearly before his friends.

"We ought to go and round up the two trucks," he finished.

"No--we must get to Griff. He must be wild, waiting without any word. I
know the trucks won't wait forever, but you can identify them in the
morning. Come on." Curt followed Bob's lead, with Al at his heels as
they entered the office corridor.

Griff's voice came to them as they reached the upper landing. He was
talking--telephoning!

"Oh--Langley! You got there! Good! What? Your uncle is gone? Gone? Gone!
Lang--where? You don't know? What'll I do, Lang? You don't know? Well, I
do!" and he slammed the receiver on its hook.

"Hurry!" urged Bob as the trio raced to the lighted doorway.

At the safe, kneeling, was Griff. He twirled the dial, clanged back the
safe door, reached for the packet of bills again.

"Here--you mustn't! You daren't. That isn't yours!"

White-faced, Griff identified Al as the latter called his warning.

"I must!" he snapped, and stood up, holding the packet.

Over the offices came the drone of the approaching airplane circling for
a landing. Al moved toward Griff.

"Get back!" Griff was furious. Bob, behind him, snatched the packet of
bills, flung it into the safe, slammed the door. Griff, with a furious
snarl, bent to recover the packet, but the door was shut.

He flung off Bob, who backed into Al and Curt.

Heedless of the roar of the airplane engine as the ship came low over
the office roofs in its descent, Bob, Al and Curt disentangled
themselves, got to their feet.

Already Griff was by the safe, the combination figures on the slip in
his hand, the dial of the safe door twirling and clicking.

"Here--what are you doing, Griff?" Bob cried out in dismay.

With a quick glance Griff measured them. His face was white, his jaw was
set, his whole attitude was that of a terrified, trembling young man who
had determined on a course he knew to be wrong but which circumstances
would not allow him to avoid.

"Don't!" exclaimed Curt.

"You daren't!" corrected Al. "Your father has stolen the books, but you
shan't----"

The safe door was wrenched open. Bob started forward, Curt at his side,
to catch Griff's hand, to prevent this thing he felt he had to do. His
fear of his father's anger was greater than his dread of the boys, it
seemed.

His hand on the packet of bills, Bob tried to stop him. Griff, with a
scowl and a wicked word, kicked Bob's shin, avoided Curt's grasp, and
stood back, his face working.

There was an interruption.

"Listen!" Al, nearest the door, called the word. They were halted,
frozen into statues with tense poses and straining ears.

A step sounded in the hall.

Instantly, white with terror, Griff flung the bills toward the open
safe, kicked the door shut, turned like a hunted animal and ran out
through an intervening door into the next office, and, with Bob in hot
pursuit, raced across the hall, into the directors' room, to its window
and down the fire escape. And Bob, at the window, felt a hand grip his
collar. He was caught!




                              CHAPTER XXIX
                              A CONFESSION


Without a struggle Bob gave up. In the dark he did not know who his
captor might be; but he reasoned that if it turned out to be Barney
resistance would be less sensible than explanation. To struggle for
escape if the hand on his collar belonged to Mr. Parsons, would be
foolish and might make it harder for his chum and his brother to explain
their situation.

In his mind's eye Bob recalled how the office had looked as he left it.
Griff had kicked at the safe door, believing the money had gone in; but
it had not! It had dropped on the floor.

Unquestionably Mr. Parsons, or Barney, or whoever held him, had come
past that office but had not stopped there, preferring to make a capture
of the only person he could put his hands on.

Bob realized that non-resistance was a wise course. As he had surmised,
he was led back toward the office. He was glad that he had done nothing,
said nothing to explain the situation so far. The man who had hold of
him, who urged him along the corridor, was Griff's father, the man from
whom they sought to save Griff.

At the office door Bob, panting and choked a trifle by the tight grip on
his coat, took in the situation swiftly.

It looked, from all the appearances, as though Al were dictating from
the slip while Curt manipulated the combination, to open the safe; on
the other hand, from another point of view, it might appear that the
pair had recently had the safe open and were closing it.

What made that more probable to an outsider's eyes was the package of
greenbacks which Al held!

"What does this mean?" Mr. Parsons, half dragging Bob along, made a
quick, nervous advance, caught the package from Al with his free hand.

"It means that your--" Al began in his imprudent haste; Bob gave him a
sharp, meaning look. Al, catching it, realizing that he had almost
mentioned Griff, whom they had previously agreed to aid, was silent.

"It means that we came back here--" Curt began and was interrupted by
the angry partner of Mr. Tredway.

"Not content with taking those books," he said angrily, "you want to
take the company money--how did you get into my desk? Pick the lock?
That adds another count against you!"

He released Bob's coat collar and strode to the desk, a flat-topped one
in the center of the room. Catching up the telephone receiver, he made a
call.

"Hello--hello! Give me Police Headquarters! Yes, thanks!"

For an instant the members of the Sky Squad were stunned.

"What's that?" Mr. Parsons spoke into the transmitter again. "He is out?
How soon will he be back? Have him call Mr. Parsons, at the aircraft
plant! Yes--perhaps I can give him some tenants for the new cells in the
police station."

He hung up the earpiece.

Bob, recovering his usual good judgment, began to consider the very
difficult situation that faced the Sky Squad.

Al, however, seldom thought before he spoke; more often than his
brother, he was sorry for hasty decisions and sharp speeches.

"You'll be sorry if you tell the Chief of Police," blustered Al.

Curt, as thoughtful as Bob, trod on the foot of the younger captive and
Al, jumping away, refused to be warned.

"I don't care!" he cried. "If he thinks two sons of a detective, and
their friend will be put in cells for trying to save--oh, all right,
Bob!--for trying to put money back into a safe--" he whirled on Mr.
Parsons at the sound of the latter's sarcastic laugh, "--that's what we
were doing! If the Police Chief arrests us--we'll ask him to arrest you,
too!"

"Indeed! Why!"

"For taking the company books away. For showing them to somebody outside
the firm--planning how to get more cheap parts into the plant. Oh, we
know all about you!"

"How do you know I had company books?"

"I saw the pages open on the table at The Windsock!"

"Indeed! Young man," he swung to Curt. "Please go into the bookkeeper's
room, unlock his book cabinet, and bring all the books you find."

Curt, surprised, took the small key from their captor, went in and
lighted the adjoining office, returning, finally, with an armful of
books.

"Do you know the books of a complete set when you see them?"

"Bob does," declared Al, still angry, but becoming a little uneasy. He
might have jumped to his decision about the books he had seen. He was
always making snap decisions!

"Examine that set, young man--er, Bob!"

"It's complete!" Bob admitted.

"Exactly!"

"Then why were you in such a sweat to get the others when we tried to--"
Al's voice tailed down to nothing; he began to see how really guilty
they could be made to seem. There was entry into the offices at night,
an open private desk, a tell-tale safe combination memorandum on the
floor, a package of bills beside the safe, for one chain of evidence;
there was an intrusion on a private conference, at The Windsock, and the
subsequent escape with the books for a second, not to think of Bob's use
of the airplane with no permission from a higher authority than a
watchman, and the infraction of State law by landing on a highway and
deserting the ship in a traffic lane. Al's bravado began to evaporate.

Bob, who had remained cool, thinking, was able to see a brighter side to
the situation.

"Please, Mr. Parsons," he began, "don't call in the police. That would
force us to defend ourselves. We could explain what we were doing and
why. But we have a--a code of honor, and we would rather have you let
things work out without the police--and reporters."

"You would really suffer more than we would," Curt declared.

"Is that so? We shall see."

The telephone bell blared. Mr. Parsons turned.

"Hello!" he spoke into the instrument.

"Father! Don't! Those fellows are protecting me! I can't let them!"

Griff stood in the office door, his face white, his lips quivering.

Mr. Parsons, catching sight of his son, stared.

"Just a minute, Griff," he said. "Hello--is the----"

"Father! You shan't! You mustn't! Listen to me. I took that money!----"

The telephone receiver dropped, hanging by its cord to swing unheeded
against the man's leg.

"I'll confess!" Griff, for all his fear of his father, of consequences,
was showing his true manliness. "I ran away, Father, because I thought I
had put the money back and locked the safe. I didn't want to be caught.
I thought I could go down the fire escape and get away. But when I saw
you catch Bob I came back and listened--I must not let these fine
friends stand a night in a cell for something I've done."

Then, haltingly, ashamed and despairing, but honestly, Griff cleared the
Sky Squad and told the truth.

"He was trying to get out of his trouble," Curt said to end the deep
silence that followed Griff's explanation, "and he didn't want to come
to you when you had so many things on your mind."

"Our cousin has gone to get money for him from Father," added Bob. "But
Father must have started for home before Lang got there, and it was only
when the man at The Windsock threatened to come and tell you and make it
look worse than it is, that Griff lost his common sense. We came back
here to meet each other and saw what he was doing and convinced him it
was a mistake."

The impulsiveness of Al prompted him to "put in his oar," but his
earlier bluster was gone and he kept still.

They watched Mr. Parsons.

His face was set and pale, his fingers worked nervously. He had his head
bent.

Bob, quietly picking up the telephone as he heard the impatient voice of
someone at the other end of the connection making it squeak, spoke into
the transmitter quietly.

"We'll call you back. Something has come up to make things different."
He hung up the earpiece.

Apparently Mr. Parsons did not notice him at all. Added to the blow
given by his son's confession that he had broken promises and gotten
into deep trouble was the knowledge that three loyal companions, with
full knowledge of his guilt had not only protected him from himself but
had shielded him at the expense of being, themselves, suspected and
unfairly accused.

Mr. Parsons looked up. He held out a hand to Bob.

"I beg your pardon," he said, "I am sorry!" Bob, smiling with some
relief, eagerly gripped the extended hand, to be followed by Curt and
Al.

Then the father turned to his son.

Three members of the Sky Squad held their breath.

"Son," the voice seemed cool and sharp, but it changed suddenly, "Son, I
guess I'd have done better to make a comrade of you than to try to rule
you with fear and threats. Come here, Griffith." The young man advanced,
hopeful, but also shame-faced. "Son, we all make mistakes. If we learn
not to make them again, that is life's lesson. I am not a judge. I
am--your father!"

Griff's hand reached out impulsively.

"I had to tell you--but I guess if it hadn't been to save these friends,
I might have gone on. I guess I'm a coward."

"I should say not!" cried Al.

"Not you!" Bob was equally emphatic.

"It took more bravery to walk in under the circumstances than to tell
your father any other time, I say!" Curt exclaimed.

"I will settle with that fellow at the roadhouse," Mr. Parsons stated,
when forgiveness was assured to Griff and the five occupants of the
office were determined to "work together" for a change, "If he has been
paid----"

"Why not meet the Police Chief somewhere and have Griff tell him the
things that are done against the law at The Windsock," suggested Al.
"Then we could all go there and give evidence of how Jenks tried to
collect twice from Griff--and maybe we would find out something
about--our own mystery. I think he is in it, some way!"

Mr. Parsons decided that he owed the Chief some explanation of his call
and, somewhat over-excited, and not his usual sensible self, he failed
to realize just what Al's suggestion implied--that they make Griff
incriminate himself, since he had played at the tables without informing
against the hotel. The Police Chief agreed to meet them near the
roadhouse, and when Mr. Parsons hung up and turned back to them he was
much more calm than they had ever seen him. "If I explain my own
purposes," he said, "it will be easier for us all to understand and get
together. I have been trying to protect my absent partner----"

"Absent?" Bob repeated the word, "your absent partner?"

"Yes. Arthur Tredway. He went into hiding."

"I know!" cried Al, "I know now! I thought the face of the man in that
brown airplane--the one who flew it--was familiar. That's Mr. Tredway!"

"Yes, my boy, you are right."

"But--" Curt was rather stunned, "I don't understand."

"Mr. Tredway--alive?" cried Griff.

"Yes, alive. This has been a very mixed affair," the partner declared.
"I knew that Arthur Tredway was alive, but I could not speak of it or
explain, because we did not know whom we could trust, and so told no
one."

"Then he wasn't--in the crash?"

Mr. Parsons turned to answer Bob.

"No."

"But why did he do it? Why did he hide and let everybody think he had
'gone West?'" Bob demanded.

"Don't you remember--crossed wires?" Curt reminded him.

That had to be explained.

"So someone crossed wires that were scraped nearly bare, in Arthur's own
ship!" Mr. Parsons was dismayed. "That proves his suspicion that
somebody meant harm to him. And that is what we hid him away to
discover. If the accidents ceased with his disappearance, he was in
danger; if not, the damage was aimed at the aircraft company."

"But you haven't found out why he was in danger--or from whom?" declared
Curt.

"No," admitted the partner. Al, fired with enthusiasm, added:

"But we will!"

Mr. Parsons was not so sure.




                              CHAPTER XXX
                          BARNEY GIVES A HINT


While the quintet waited for the taxicab which Mr. Parsons summoned from
town, Griff put the money back in the safe, thankful for his escape.
Bob, Curt and Al expressed their elation that he was freed from
suspicion, and Barney arrived.

"The watchman called me," the manager explained. "Things got a bit too
exciting out here and he thought I ought to know. What is there to tell
me?"

The explanations took up the time of waiting.

"Hm-m-m." Barney was pleased but thoughtful. "Glad to learn my best
friend's partner is cleared," he nodded at Mr. Parsons. "Certainly I'm
delighted that his son is all straight. And Tredway is alive! Glory be!
I'm gladdest about that."

"I knew you would be," agreed Mr. Parsons.

"The man who gave me everything I have, made me the manager of his
plant! I'll say I'm glad he's all right. Well, let's go see that
ex-pilot and his wicked two-autograph ally!" he grinned at Al.

"I think we ought to try to catch those truckmen first," suggested Curt.

"Oh, let them alone," argued Barney, and Mr. Parsons agreed.

"You know what they were doing," he told Curt. "All you have to do now
is check the stuff that is unloaded from our truck in the morning. If
that turns out to be poor material, trace the other truck, get your
proof--and at least one part of the mystery will be easily solved."

They went out and packed into the taxicab, giving its driver direction
for meeting the Police Chief at the edge of the picnic grove.

When they got there and related their experiences they were daunted to
find him decidedly lukewarm about "rounding up" the ex-pilot and his
roadhouse manager.

"I don't think the idea is so good," the Chief of Police stated.
"Griffith Parsons has no receipt. He can't actually prove that he paid
real money, or that he paid at all. Anyway, now that his father knows
the whole business, that fellow, Jenks, hasn't a chance to collect
again. He won't dare try. Just what do you want me to do?"

"There's this note put on the airplane, and his trying to avoid showing
his handwriting by giving me two autographs," Al suggested.

"In a way I'm sorry to destroy that clue," said Mr. Parsons, "but when
we get to the roadhouse you will see that it has no value."

"What did you want me to do?" repeated the police official.

"We thought of facing the manager, Jenks, with Griff's evidence of how
he permits gambling to go on--and other things outside the law--and
making him tell us what he knows," Bob urged.

The man shook his head.

"Oh, I know what you're thinking," the officer chuckled as he eyed Bob,
Curt and Al. "Graft--hush-money! But that isn't it at all. As far as
Griff's information goes, we'll take care of that better by making a
raid when the place is crowded and the barn is actually in use for
illicit purposes. But, don't you see what you are doing?"

The chums shook their heads.

"I do," said Barney, and Mr. Parsons agreed again. "If we offer to make
him tell with a threat of what we will do if he refuses,--we are
'compounding a felony' if we get him to tell anything and don't go
through with the legal steps on the face of our evidence."

"That's it."

"Oh, well," Barney saw how disappointed the three chums were, although
they admitted the justice of the official's attitude, "let's go out and
see my old patron and comrade."

The Chief of Police agreed to look into the charges Griff had made and
turned his car to return to his home, while Barney, in one cab with Bob
and Al, and Mr. Parsons in the one they had called, with Curt and his
own son, went on.

There was a vociferous greeting between Mr. Tredway and his plant
manager.

"Why didn't you tell me you were all right?" he cried, pumping the plant
owner's hand, slapping his back, and, as Al said later, "almost kissing
him," while the mysterious stranger, and the others watched with various
feelings.

"I had to make my plans in secret," Mr. Tredway retorted. "Not even my
partner knew until tonight. But--let us get acquainted, all the way
'round."

He turned to the mystery man behind him.

"This is my brother," he presented the man, "and so these are the three
young men who have worked so hard to solve the mystery of my crash into
the lake!" He shook hands and they selected a private dining room on the
second floor for a midnight repast.

"Well," he said, smiling pleasantly at the three rather silent youths as
the first course, a hot, nourishing soup, was served, "have you solved
the puzzle of the mystery crash?"

"I think we have--but not all, sir," replied Bob. "I think I can put
together what happened, but not why it had to happen."

"Go ahead," Mr. Tredway encouraged.

"Yes, do," urged Barney. "I admit I'm stumped."

"Well, sir," Bob, without trying to be vain, spoke frankly. "We got
mixed up and puzzled, at first, because we were trying to solve a lot of
things by connecting them with your--disappearance."

"And we made the mistake of suspecting everybody," interrupted Al.

"That mixed Griff's case in, and his father's," agreed Curt, and he
turned back to give Bob the center of the stage.

"You didn't know whether the damage to airplanes was aimed at the plant
or at you direct," Bob told Mr. Tredway, who nodded. "You had two
airplanes--both alike, except one was the Golden Dart and the other was
the Silver Flash."

"Exactly. And I thought," Mr. Tredway interrupted, "if the guilty person
knew which airplane I meant to deliver, he would damage that one and so,
at the last minute I changed my ship, after saying I was going to
deliver the Golden Dart I took off in the Silver Flash----"

"And you were right," gasped Al. "When we flew the Golden one her rudder
cable was frayed and broke."

"Right, my young friend. And nothing was wrong with the other."

"Then how did you crash it--why did it crack up?"

Mr. Tredway looked to Bob for an explanation, desiring to test the
youth's skill at deduction.

"I haven't much to work on," Bob said modestly, "but this is how I think
you did it:

"Your brother flew here in the brown ship and hid it in the field,
leaving the note to show you it was ready."

"And then?----"

"You took off early, and then set down the big cabin ship on the
turf--that accounts for the deep ruts--and the ship was in the way so
you dragged it into the stubble until the brown ship got up, then took
the cabin craft into the air----"

"I fail to see what the brown airplane, and Arthur's brother, have to do
with it," Barney broke in.

"Mr. Tredway's brother had to be there to bring down the cabin 'plane,"
Bob explained. "At least that's the only way I can see for the tracks in
the field, and the crack-up, to fit the conditions," he paused.

"You mean--they exchanged ships? Arthur landed the cabin crate and then
flew away in the brown one, while his brother crashed the Silver Flash?"
Barney demanded. Tredway nodded as did his brother.

"The young man is correct in his deduction," the latter said. "I had to
come and exchange ships with my brother and then crack up the Silver
Flash to give the idea that its pilot--and my brother had taken off in
it!--had gone into a mudhole or under rocks in the lake."

"What did you expect to gain by that?" asked Barney.

"Removing one partner," Mr. Tredway smiled, "gave the other one 'a free
hand' if he was in any way guilty, or you, Barney!"

Barney turned red.

"Do you mean to say?----"

"No, I did not suspect you, I only wanted to get away and see what
happened, and who did it."

"These young men have cleared most of us," stated Mr. Parsons. "They
have done more! They know how the good parts are taken and cheap ones
are substituted." He explained about the trucks.

"But we can't solve the mystery of why you brought books here and then
said the company books were all at the plant," argued Al.

"I found a small set of duplicate books--that is, what we would call
'fake' books--private books in the cabinet," began Mr. Parsons.

Barney bent forward.

"Where did you find those? I had them in my own desk!"

"That's where I took them from. You see, Barney, as long as we all
suspected each other it was wisest for me to check them. Not that I
accuse you, because they were in your desk. You were checking up, also,
of course."

"I'm not finished either," declared Barney. "But--as long as Arthur
wanted a look at them, it's all right with me."

"We have them safe," said Curt. "And the brother is the mysterious man
with the dark beard whose motorcycle Griff used, and it was he who was
in the supply room, the other night."

"I was," said Mr. Tredway's brother. "I came, with his key, got in the
private gate, went up the fire escape and down to check up in the supply
room--until Griff, running off with my motorcycle, made me suspicious,
scared and anxious. So I left."

"And I came here to see Arthur's brother," said Mr. Parsons, and Griff,
looking ashamed added, "--and I ran away!"

"But we don't know who damaged the crates, or if it was against Mr.
Tredway or just spite work against the company," Al said. "The mystery
crash has failed to bring that to light."

"Yes," Barney suddenly leaned forward, "I've got to go, out and dismiss
my taxicab--it's eating its head off--but first I'll give you a hint to
chew over while I'm away."

"What?" several spoke the question in unison.

"Suppose the motive was revenge," Barney spoke very low, and Bob,
watching some curtains, at a locked side door, thought the breeze must
be stirring them, "suppose there was once a pilot at the plant and that
Arthur had to fire him and----"

"You don't mean to say!--" Mr. Tredway bent close, excited. "The pilot I
once discharged? Why--he's the owner of this place. I'd never dream----"

"All the same--chew it over!" Barney rose. "I suppose you'll be flying
back--you won't stay here tonight." Tredway shook his head.

"Be right back," Barney said. Bob, as the others chatted softly and
excitedly, followed the departing manager with his eyes. He had thrown
suspicion on several, had Barney. Also, he had been the only one who
inspected and then reported on the Silver Flash, that nothing had been
found tampered with! And--he had chased Lang and Bob to see Bob's
detective father! What a lot of curious facts, Bob mused!

And when Barney rejoined them a moment later Bob was still musing!

"I think it would be a good idea for all of us to stay," suggested Mr.
Parsons. "It's after midnight, and these lads must be worn out, with all
their pedaling to and fro. We can telephone their homes."

"You may all stay," said Mr. Tredway. "But until we prove something I
shall keep out of sight. Especially if the ex-pilot is apt to be around.
I'm going to warm up my brother's airplane and hop back to the airport I
came from."

They all parted. Curt declared he wanted to secure his forgotten
bicycle, Bob and Al were sure they had better go on home if Mr. Parsons
would let them take the taxicab. He decided that, after all, he and his
son had better go home. The meal was finished. Mr. Tredway, going by a
side hall, and down back stairs, sought to avoid recognition while his
brother agreed to watch the ex-pilot at every chance.

Bob and Curt found the bicycle safe, and trundled it to the luggage rack
at the back of the taxicab.

Then Bob turned suddenly.

"Stay here," he said, "I want to say something to Mr. Tredway--he's
warming up the airplane."

"Forget something?"

"No--recalled something!"

As he reached the man so mysteriously lost and so suddenly discovered
Bob caught his arm and spoke very earnestly.

"For the sake of your safety," Bob whispered, "take off, just as you
planned--but only go to the cornfield--set down as soon as you can--and
then--look for--crossed wires!"

In a flash he was beyond questioning!




                              CHAPTER XXXI
                           "ONE MORE PROBLEM"


Bob did not delay a moment after he delivered his solemn warning to Mr.
Tredway.

As quickly as he could he located the plant manager.

"Barney," he said earnestly, "don't stay here tonight! Come home with
us. Stay with the Sky Squad."

"In the name of Sam Hill--why?"

"You forgot where you were, didn't you, when you spoke about the----" he
lowered his voice, glanced around, spoke carefully, "--the ex-pilot as
the one who had a motive for injuring Mr. Tredway?"

"Well--I guess I was thinking pretty much of what I was saying."

"I know you were."

"Well--did you hear anything or--see anything?"

"I'm sure I heard something. You didn't think, but there's a curtained
door in that private room we used. How do you know Jenks or--the other
one--might not have heard you?"

"Lad, you're quick! Right, too. Maybe I'd better go on. But I won't need
to stay with you."

"Oh, you'd better. We can take turns watching!"

"Fiddlesticks! It's not as dangerous for me as that!"

"At least come back in the taxi with us."

"Oh, all right. I'll do that. But I'll go on home, then."

"Won't you come on, please--right away?"

Barney, half-amused at Bob's concern, and partly wondering what caused
it and if he actually had been spied on, overheard, and realizing even
better than did Bob, he thought, how dangerous such an accusation might
be, Barney agreed.

The ride back to town was taken up with discussion of Barney's hint but
through all the talk Bob was rather quiet.

It was decided that the three members of the Sky Squad would be taken
home first, then Griff and his father would go on, leaving Barney to
finish the ride to his own home.

As the car drew up in front of Bob's house and Al began saying his
goodnight, quite sleepily, Bob turned to Mr. Parsons.

"What do you say to going back to the plant, after you drop Griff, and
getting the real set of company books, and bringing them here. We can
work on them together, and see if there is anything in the private set
that doesn't agree with the others."

"Why not wait until morning?" suggested Mr. Parsons. "Aren't you worn
out?"

"What books?" Barney asked. "Oh--that's so. I remember. You said you had
them. Put them away carefully! Don't leave them out."

"Oh, we will," agreed Al, overhearing. "We'll put them in the big desk
in Father's study and lock them up."

"Well, goodnight," said Curt. He had been invited to stay but he
preferred to go on home. Bob threw in a suggestion.

"At that," he said, "Curt, why don't you let me telephone your mother,
and you stay. And Barney could wait with us till Mr. Parsons comes
back."

"Well, come to think of it, why not?" Barney decided. "If it won't wake
up your folks." Bob assured him it wouldn't. His mother must still be
waiting up, he declared; there was a light burning in his father's
study.

"Good grief!" he cried, "I never thought--supposing Dad has come home?"

"I'll bet he has," Al agreed.

"Let's go and see--will you come in with us?" he addressed Barney, and
the latter cordially agreed.

"I guess we'd better let you wait in the living room till we see whether
it's Dad or Mother. She might not be dressed for company--if Mother is
sitting up." Barney agreed to wait, and Al went to the door to call Curt
in to telephone home.

The den, into which Bob turned, closing the door quietly, was occupied,
as he had all along suspected it would be, by his father.

"I heard that you weren't in the other city," Bob said, after a hasty
greeting. His father saw his eagerness and let him talk. "Lang flew
there to get help--" he sketched very swiftly the incidents of the
night. "Now, Father, what brought you home? Have you?----"

"I have suspicions--yes."

"Then you've been working on the mystery?" Bob asked.

"All along. I pretended to be busy on another case because----"

"You suspected somebody!"

"From the start. Yes. Did you?"

"Not until tonight. But I know it's the same person, and I've got him in
the living room and I want to pretend to him that we are guarding him
from some one else, while we keep guard to see that he doesn't take
fright and escape."

His father framed a name and Bob nodded.

"What is your proof?" demanded his father.

"He came to a detective at the very first. He has put suspicion on
everybody else. He seems terribly anxious about those books."

"Circumstantial evidence justifying suspicion, but not proof.
However--I've learned that some people, probably using assumed names--it
may all be the same person--have been changing aircraft stock into gold.
What is your plan, son?"

"We must keep him from guessing that we suspect--and keep him where we
can watch him. The way I plan, if you agree, is this. Father, if he is
the guilty one, he is terribly dangerous. He must have crossed wires on
Mr. Tredway's airplane, before the owner left the plant--hoping he'd
have a short-circuit, set the gas on fire and come down in flames. Then
he thought the Golden Dart was the cabin ship to be flown and he frayed
the rudder cable. When he discovered the other ship was going he might
have crossed wires on that--remember, he mentioned 'crossed wires' back
in the other city? And he's the only one who inspected the Silver Flash
when she crashed and was hauled in. So we must keep him here where we
can hold him if he makes a move."

"Right. Get him in, son. We will pretend to study the books, and I will
watch his reaction."

"And if he doesn't betray himself?----"

"We will let him go. He cannot leave tonight because if he has been
taking stock and exchanging it for gold, he probably had to bank it--he
wouldn't leave it in his house, would he, son?"

"We can have detectives watch his house all night. Father, fix it with
the Chief of Police while I get him."

Barney was ushered in, Al and Curt joined them and the three of the Sky
Squad lined up on the davenport to watch Barney as the detective
discussed the case.

But Barney did not betray any uneasiness. He was clever, Bob decided.

Mr. Parsons, for whom Al watched to let him in without awakening Mrs.
Wright, brought other books and they were all busy.

"We've discovered something!" Al exclaimed, after half an hour.

"Sky Squad will now report!" chuckled Barney. He turned to Bob.

"Go ahead, Chief Pilot!"

Bob, very serious, nodded.

Was Barney getting fidgety? Or, was he simply eager?

"What have you found?" his father prompted him.

"We've solved one mystery--how the bad parts are coming in," said Bob,
confidently. "Curt, bring the false ledger and the real one."

All heads bent interestedly.

"Notice how those tiny pencil 'ticks' are made in the beginning of some
entries?" Bob pointed to several. "There aren't any in the regular
ledger, but the entries correspond, and they are always worded in a
queer way. See this one, about fabric: '10 bolts fabric, cotton, quality
A--dash--X--one hundred,'" he quoted. "Now all the entries that are
ticked in the false ledger are backward like that--and the same in the
regular book, but no others except the ticked ones are!"

"That's curious," muttered Barney. "What else?"

"Here are several bills of lading that weren't entered Saturday, just
slipped into the back of the regular ledger," Bob drew them out and
unfolded them. "One is all right, but the other is made out
backward--the same as the ticked ones--and it isn't a real bill of
lading at all, because it is dated for today, and the shipment that
arrived today isn't to be delivered until tomorrow and we saw the two
trucks exchanging goods on the byroad--or, Curt did."

"Very clever, but what does it prove?" asked Barney.

"This bill of lading being dated ahead and being one of the 'backward
wording' sort, shows that those are the entries that are 'queer.' That
solves the mystery, because we know how those things are being
substituted tonight."

"But who does it incriminate?" asked Barney.

"Why--whoever's writing matches this."

"Then the bookkeeper is due for a call on the carpet--maybe worse," said
Barney. "That's his book, and the false set is the same handwriting!"

"That settles that mystery and leaves only the one about Mr. Tredway's
possible evil wisher," said Mr. Parsons.

"Why, that's attended to--all we need to do is to watch that ex-pilot,
and Mr. Tredway's brother has agreed--" Al paused. The den private
extension telephone was ringing.

"It's for you, Bob," his father said. "Who'd be--oh, Mr. Tredway! How
are you? Glad you're 'alive and kicking.' Yes, this is Wright. My son
stole a march on me, finding you. Here he is."

Bob bent over the desk.

"Hello...." he said amid a tense silence. "Oh, did I guess right?... You
didn't go on? ... set down in the cornfield ... fix it in the
morning?... Yes. Thank you, sir, for calling. Yes, we just got here."

He replaced the receiver and turned to the interested, expectant
company.

"Another of the puzzles solved, and I guessed rightly," he said.
"Barney, when you suspected the ex-pilot, I thought it might be that
he'd do the same as he had done on the airplane I piloted--Mr. Tredway's
own sport craft. You know why I had to set it down?"

"No--because the other man--Arthur--chased you down?"

"No," said Bob, slowly. "You mentioned the ex-pilot having access to the
'planes. Well, on the brown ship--the wires were crossed tonight!"

"Oh!" Barney gasped, and recovered from his startled amazement. "You
don't say! That's bad for--the ex-pilot."

"But it disposes of one mystery--who! He was probably there at The
Windsock and heard you--don't you suppose?"

"Looks like it. Well, now, that clears up----"

"All but one more puzzle," said Curt. "Who's getting away with the small
parts, and valuable instruments?"

"I can settle that!" said Barney. "Sandy Jim, the rigger Al was put to
work for--remember him sending you to his house with a lot of parcels
supposed to contain junk for his kid?" Al nodded, dismayed. It hurt to
hear that honest-looking Sandy was so wicked. But Barney seemed to have
the correct idea, as the evidence indicated.

"We'll round them up tomorrow." Barney rose. "Suppose I take those books
along with me? I'll bring them in early in the morning."

"Fine!" Bob jumped up, gathering the books. "There's a Summer shower
wetting the streets--I'll wrap these in paper for you."

When he returned with the parcel all goodnights had been said and the
party broke up.

"Son," said Mr. Wright to Bob, "what do you think now?"

"I can't say. He acted all right. But he always has done that."

"Who?" Al was sleepy but curious.

"Barney!"

"You don't suspect Barney?"

They nodded.

"But how can you? He has helped us, and he's Mr. Tredway's friend and I
always thought--er----"

"A criminal had to have a motive?" prompted his father. "I attached no
importance to one fact I have discovered, until I felt sure of Barney's
guilt. Now I do. This might be his motive! Years ago Mr. Tredway won the
girl whom another pilot was courting. The man went from bad to worse,
threatened--and then disappeared."

"Jealousy! Hate!" gasped Curt. "But Barney!----"

"Of course that was not the pilot's name. He must have changed his name
as well as his appearance."

"Then, Father, how did you know it's Barney. How about the ex-pilot?
Couldn't he?----"

"No, Al. He worked for Mr. Tredway after the latter married."

"Well--then--good cracky! Bob--you gave the culprit all the evidence in
those books--to destroy!"

"No!" Bob smiled. "Dad's encyclopedia is shy four volumes, and there are
three vitamine books gone, and Barney has them. The real books are in
their places on our shelves!"

Then they did compliment him!




                             CHAPTER XXXII
                                FLIGHT!


When the sun peered through dispersing Summer storm clouds it saw three
alert, wide-awake youths, a little tired but very tense, in the testing
field of the Tredway aircraft plant.

With them were Mr. Tredway, the Chief of Police, Mr. Parsons and Griff.

"Is Tredway's speed plane fueled up," Mr. Wright came over from the
offices where he had deposited the company books in readiness for later
use: his question was addressed to Griff.

"Ready, sir," the young son of Mr. Tredway's partner responded.

"All plans arranged, Chief?"

"We've got a net spread that Barney Horton couldn't escape if he was an
eel. One of my best detectives has been outside his house ever since he
went in from the taxi, at one 'a.m.' Those two men over by the offices,
getting ready to dig a trench, are two picked men of my headquarters
staff. Every motorcycle man, every traffic man, all our roundsmen and
policemen are on the alert."

"I simply cannot believe it of Barney," Mr. Tredway was as doleful as
though they were planning to arrest him, instead of his plant manager,
"I took him in and gave him every opportunity, taught him all he knows,
pushed him to the top. To think--"

"Hatred for a fancied wrong is a terrible force for evil," said Mr.
Wright.

"But he doesn't look a bit like the man who was trying to win the woman
who became my wife."

"By the way," interrupted the Chief of Police, "she hasn't appeared at
all in this--have you separated? Isn't she----"

"Oh, yes," quickly, "she is alive. My wife is away in Europe. That is
the reason I decided to--disappear. I knew that news of it would not
reach her before I 'came to life.'"

"But if Barney is the guilty man," Curt was still dazed, "why did he
turn suspicion on that ex-pilot at The Windsock?"

"He tried to turn suspicion on everybody," retorted Mr. Wright. "It is a
favorite trick of a guilty person. He has practically accused the
bookkeeper, the supply clerk, Sandy Jim, the rigger and the man you
mentioned."

"But he's free," Al spoke. "Why didn't you arrest him while you had him
at the house showing him the books?"

"You must remember one fact, my young 'Sky Squadder,'" the Chief of
Police commented. "Circumstantial evidence, and suspicion are one thing.
Proof of guilt that will stand in court against a clever lawyer is
something quite different."

"In other words," Mr. Wright explained, "we feel, with absolute
conviction, that Barney is our man. We haven't any actual proof. We must
wait until he makes some open move. Bob, cleverly discovering Barney's
supposed guilt because he saw Barney make that excuse to get out to the
airplane when he said he wanted to dismiss his taxi, did all he could to
keep the man close to his Sky Squad; but Barney was clever."

"I thought he would make a try for the books during the night if I got
him to stay with us," Bob admitted modestly. "Then, when he refused to
spend the night with us I hoped he'd discover that we had substituted
other books for the ledgers, and would try to get in our place to get
all the incriminating evidence. But," dejectedly, "he was too clever for
that, even."

"How do you expect him to make an open move, if he's all that wise?"
asked Griff.

"Well," Mr. Wright spoke up, "some one has been quietly exchanging
company stock, turning some into gold, here and there. I think it was
Barney's work under assumed names, to get his money into shape for
escape. We have made him see that we know how the cheap, shoddy supplies
are coming in, and other things: he will try to get away."

"The paying tellers of the town banks are on the watch. The first minute
he comes to close his accounts, as he will do before he takes a train,
we will be informed. Before he goes he may try to destroy the false
account books, and leave only conviction of his guilt, but no real,
legal proof."

"But--" Al was still somewhat puzzled. "Bob, how did you come to suspect
Barney at all?"

"Do you remember me telling what was said when I flew with Lang to see
Father?" As Al and Curt nodded, Bob added, "Barney used a phrase about
'crossed wires.' Then I found crossed wires in Mr. Tredway's ship last
night, and later Mr. Tredway found wires chafed, and led across each
other, by his brown 'plane carburetor. It was the quickest way to
endanger a ship--the spark could set fire to free gas, and might not be
noticed in daylight. Barney had time to do it."

"When he went out? I see," Curt said. "But, Bob, you thought some one
was listening, watching--you told Barney so."

"I still think some one was spying over our dinner--but it may have been
the manager, Jenks, who may be 'in' with Barney."

"Speak of the--" Mr. Tredway gave a warning glance as he began the old
adage, "speak of the devil, he's sure to appear."

To their amazement, Barney came through the gates. He was calm, quiet,
not at all furtive or frightened.

"What was the idea of that trick you played with the books?" He patted
the package he carried. Bob was confused.

The arrival of the rigger, Sandy Jim, coming early to complete work on
the new airplane for which the owner was in such a hurry, enabled Bob to
hide his confusion as his father answered, quietly, "I'll tell you that,
Barney."

"All right. Tell me."

Bob, who turned his head to hide his crimson face, and who went to greet
Sandy Jim, with Al, as an excuse to avoid an explanation that might
upset their plans, was surprised at the look on Sandy Jim's face.

The man was staring at Mr. Tredway as though he saw a ghost.

"I--I--thought that man was----"

"Hello, Sandy!" Al greeted, taking the amazement as natural, since
everyone around the plant supposed the owner to have gone under the mud
in the Silver Flash, "ready for work early."

"Ye--yeah! How'd he get here?" He jerked a thumb toward Mr. Tredway.

"In a taxi."

Bob took over the explanation, giving Sandy enough of the former
happenings to enable the rigger to recover from his surprise.

"I'm right glad," the man stated, finally. "Now--Al, you get some of
your crowd together and fuel up this new crate--soon as a pilot shows up
we want it tested. I may have to make some changes in the wire tension
and balance--get busy, me lads!"

Al eagerly agreed, seeing that their carefully planned "coup" had fallen
through. Barney, listening to Mr. Wright, to Mr. Tredway, to the
latter's partner and the Chief of Police, trying, all together, to give
him a "third degree," began to laugh.

"That's a good one!" He threw back his head, roaring his mirth. "So I'm
the culprit, eh? Ho-ho! Oh, my, that's rich. Clever Sky Squad you have,
Wright! Ha-ha-ha-ho-ho! Here I am doing all I can to help my partner,
trying to solve the puzzles he couldn't untangle--and I'm to be
arrested!"

"No one spoke of arrest!" the Police Chief hedged. "Are you sending some
one else to get your banked gold?"

"Banked gold?" Barney dropped his jaw as the question was shot at him.

"Converting stock!" snapped Mr. Parsons.

Barney stared and then smiled. "All the stock I ever had is in my safe
deposit box--come on! I'll show you, at the bank."

They were puzzled. Arthur Tredway was eager to claim that his friend and
protege was innocent.

The others were compelled to admit as Bob mentally decided, that
Barney's face, manner and actions were open and honest.

"That's enough gas," said the rigger. "Now, Al, fill her up with oil--I
want to see Mr. Tredway." He descended from the aircraft, went to his
employer and with many protestations of delight gripped his hand.

"See here," he urged, "Mr. Tredway, this crate they're fueling is in a
big rush. I have to make adjustments for balance before she is
delivered. Can't you take her up?"

"Why not?" Mr. Tredway was anxious to get into action since he had
agreed to "return to life."

"Hey--Bob--got her filled? Warm her up for Mr. Tredway."

Bob nodded, consulted the brand new instruments and noted that the fuel
and oil registered at "full."

"Gas on--switch off," he told Al. "Whirl that prop, Al."

His brother did his bidding. It took several trials to start the new
engine but Bob got it going and then drew back the throttle to idling
speed and went over to rejoin the group.

"I don't think Arthur ought to take that crate up," Barney was half
laughing. "Of course I know that the only wires I ever crossed was when
I flew my crates over telegraph lines--but he might think I had 'em
crossed in this ship!"

"Oh, no!" Tredway laid a hand on his protege's shoulder.

But Bob was not watching Barney.

His eyes were fixed on Sandy Jim, and he beckoned to his father.

Hurriedly, rapidly, Bob spoke to his father. The detective nodded.

"I'll get the speedster of Mr. Tredway's warmed up, too," Bob said
softly, "in case----"

To Al's amazement and Curt's astonishment the head of the Sky Squad
beckoned furiously. They followed.

"See if there's gas and oil in this," he urged as he led them to the
ship he had flown the night before, returned to its field by Mr.
Parsons. "Listen, fellows----"

As he busied himself making ready to start the motor, getting the nose
of the sport 'plane into the wind, Bob explained.

What he said startled his comrades.

"While Mr. Tredway was joking Barney about the crossed wires, did you
see Jim's face?"

"The rigger?" Al exclaimed, "you mean--when he got white?"

"Yes! Listen--gas off, switch on. Give her a spin, Curt."

As the engine took up its roar, he clambered in again, leaned far over
the edge to Curt, while Al climbed into the after seat.

"Sandy Jim turned white," he said above the engine hum. "I think we've
found the real--watch, fellows! Father is going to tell Barney in front
of Sandy Jim about the crossed wires."

"Jim is acting nervous," added Curt. "He's turning--the chief has
grabbed his arm. Now Dad is going to say to Barney that he's guilty,
that he hates his benefactor because of the other man winning Barney's
girl--of course we know it's Jim, now--watch him! Jim's being accused
now--look!"

Baffled, his face displaying his guilt, Sandy Jim fled to the new
airplane.

Without an instant of delay Bob widened the throttle opening!




                             CHAPTER XXXIII
                           THE SKY SQUAD WINS


Roaring across the runway, Bob's one purpose was to use the airplane as
a missile, to run it into the other before Sandy Jim could rise. In that
he failed. The other ship was up, and Bob knew that he had so much speed
that he must take off or ram into a hangar.

By a spurt of the cold engine, risking a stall to get his trucks over
the hangar, Bob soared.

Leveling off, he glanced around. To his amazement he saw Al snapping on
his safety belt in the rear cockpit seat. Al waved a hand, pointing to
one side. And Bob looked.

"He's having trouble," Al screamed. "He's working on something!"

Bob began to climb. If he could force Jim to earth as he had been herded
the night before--

Jim saw his move, and with a demon's venom drew a weapon and began to
fire.

But Bob sideslipped, dropped steeply into a dive to come out of the
slip, and as he drew the ship to level flight, heard something strike
the prop, saw it shatter.

Jim had flung the metal gun so that the airplane ran into it.

Bob began to look for a way to spiral back to the testing field. His
propeller, with a blade shattered, was useless.

Al screeched again. To the west, coming fast, was a ship they both
recognized. Lang was returning in Griff's speedster. Also, as Al pointed
out, the cabin 'plane was rising from the landing field.

Al was so excited that he waggled the stick.

Then Bob saw!

Forestalled by the approach of Lang, with the other ship rising to
chase, with his engine functioning badly, and the resulting distraction
of attention, Jim's safety was endangered.

The very thing that he had done when he planned to urge Mr. Tredway to
test the 'plane--crossing two wires--had prevented his escape.

The new carburetor, leaking, dripped a rich gas and air mixture onto the
sparking wires--there was a flash of flames as Bob looked.

Almost he forgot his own purpose, but with steeled will he held his
tight spiral, saw the cabin ship was out of his way, shot the field, and
landed.

When Lang and the others joined him beside the smoking ruins of the new
ship, they saw Sandy Jim, who had tried to escape by jumping before the
flames reached him.

Wrenched, broken, bruised, he was still able to talk.

"Come through, Jim--what's the truth?" asked the Chief.

"I hated Tredway from the time he got the girl I wanted to marry," Jim
panted, as they gave him water. "I went from bad to worse--went to the
dogs. I got in with tough men, tried prize-fighting, that's how my face
got changed, so I wasn't easy to remember and recognize.

"Laid low for a while, then I gave up plans for revenge, and decided to
come to work here to be close to the woman I loved, only, last Fall, she
went away. So I knew Tredway had drove her to separate--"

"You're crazy! My wife went to Europe for a long visit with relatives in
France!"

"Honest? Then all my hate was on a wrong idea. Well, you know most of
the rest. I damaged ships, worked with the bookkeeper and the supply
clerk and a manager of The Windsock to substitute cheap stuff for good,
sell the good and ruin the plant--but it was all no use--and started on
a wrong idea--no use to say I'm sorry--but--well, boys, handle me
easy--I'm no good, but I can feel pain!"

In that fashion the culprit confessed.

"I feel sorry for Jimmy-junior, and the man's wife," said Curt, after
the ambulance had taken Sandy Jim to the hospital.

"Jimmy-junior isn't his son," explained Mr. Parsons. "He is the son of
Sandy's brother, whom Jim took to raise. It would be a good idea if you
young men took him into the Sky Squad now, to take his mind off his
sorrow."

"But I saw his mother and I thought she was Jim's wife," said Al.

"No, she's Jimmy-junior's mother, but Sandy's sister-in-law."

"Then let's go," urged Bob. "It's just about time to wake up our new
member."


                                THE END




                          Transcriber's Notes


--Copyright notice provided as in the original--this e-text is public
  domain in the country of publication.

--Silently corrected palpable typos; left non-standard spellings and
  dialect unchanged.

--In the text versions, delimited italics text in _underscores_ (the
  HTML version reproduces the font form of the printed book.)







End of Project Gutenberg's The Mystery Crash, by Ardon Van Buren Powell