We had left the offices of Interstellar Voice three days ago, Earth time, and now as the immense disc of Jupiter flamed across the sky, entered the outer limits of the Baldric. Grannie Annie strode in the lead, her absurd long-skirted black dress looking as out of place in this desert as the trees.

Flagpole trees. They rose straight up like enormous cat-tails, with only a melon-shaped protuberance at the top to show they were a form of vegetation. Everything else was blanketed by the sand and the powerful wind that blew from all quarters.

As we reached the first of those trees, Grannie came to a halt.

"This is the Baldric all right. If my calculations are right, we've hit it at its narrowest spot."

Ezra Karn took a greasy pipe from his lips and spat. "It looks like the rest of this God-forsaken moon," he said, "'ceptin for them sticks."

Xartal, the Martian illustrator, said nothing. He was like that, taciturn, speaking only when spoken to.

He could be excused this time, however, for this was only our third day on Jupiter's Eighth Moon, and the country was still strange to us.

When Annabella C. Flowers, that renowned writer of science fiction, visiphoned me at Crater City, Mars, to meet her here, I had thought she was crazy. But Miss Flowers, known to her friends as Grannie Annie, had always been mildly crazy. If you haven't read her books, you've missed something. She's the author of Lady of the Green Flames, Lady of the Runaway Planet, Lady of the Crimson Space-Beast, and other works of science fiction. Blood-and-thunder as these books are, however, they have one redeeming feature—authenticity of background. Grannie Annie was the original research digger-upper, and when she laid the setting of a yarn on a star of the sixth magnitude, only a transportation-velocity of less than light could prevent her from visiting her "stage" in person.

Therefore when she asked me to meet her at the landing field of Interstellar Voice on Jupiter's Eighth Moon, I knew she had another novel in the state of embryo.

What I didn't expect was Ezra Karn. He was an old prospector Grannie had met, and he had become so attached to the authoress he now followed her wherever she went. As for Xartal, he was a Martian and was slated to do the illustrations for Grannie's new book.

Five minutes after my ship had blasted down, the four of us met in the offices of Interstellar Voice. And then I was shaking hands with Antlers Park, the manager of I. V. himself.

"Glad to meet you," he said cordially. "I've just been trying to persuade Miss Flowers not to attempt a trip into the Baldric."

"What's the Baldric?" I had asked.

Antlers Park flicked the ash from his cheroot and shrugged.

"Will you believe me, sir," he said, "when I tell you I've been out here on this forsaken moon five years and don't rightly know myself?"

I scowled at that; it didn't make sense.

"However, as you perhaps know, the only reason for colonial activities here at all is because of the presence of an ore known as Acoustix. It's no use to the people of Earth but of untold value on Mars. I'm not up on the scientific reasons, but it seems that life on the red planet has developed with a supersonic method of vocal communication. The Martian speaks as the Earthman does, but he amplifies his thoughts' transmission by way of wave lengths as high as three million vibrations per second. The trouble is that by the time the average Martian reaches middle age, his ability to produce those vibrations steadily decreases. Then it was found that this ore, Acoustix, revitalized their sounding apparatus, and the rush was on."

"What do you mean?"

Park leaned back. "The rush to find more of the ore," he explained. "But up until now this moon is the only place where it can be found.

"There are two companies here," he continued, "Interstellar Voice and Larynx Incorporated. Chap by the name of Jimmy Baker runs that. However, the point is, between the properties of these two companies stretches a band or belt which has become known as the Baldric.

"There are two principal forms of life in the Baldric; flagpole trees and a species of ornithoid resembling cockatoos. So far no one has crossed the Baldric without trouble."

"What sort of trouble?" Grannie Annie had demanded. And when Antlers Park stuttered evasively, the old lady snorted, "Fiddlesticks, I never saw trouble yet that couldn't be explained. We leave in an hour."

So now here we were at the outer reaches of the Baldric, four travelers on foot with only the barest necessities in the way of equipment and supplies.

I walked forward to get a closer view of one of the flagpole trees. And then abruptly I saw something else.

A queer-looking bird squatted there in the sand, looking up at me. Silver in plumage, it resembled a parrot with a crest; and yet it didn't. In some strange way the thing was a hideous caricature.

"Look what I found," I yelled.

"What I found," said the cockatoo in a very human voice.

"Thunder, it talks," I said amazed.

"Talks," repeated the bird, blinking its eyes.

The cockatoo repeated my last statement again, then rose on its short legs, flapped its wings once and soared off into the sky. Xartal, the Martian illustrator, already had a notebook in his hands and was sketching a likeness of the creature.

Ten minutes later we were on the move again. We saw more silver cockatoos and more flagpole trees. Above us, the great disc of Jupiter began to descend toward the horizon.

And then all at once Grannie stopped again, this time at the top of a high ridge. She shielded her eyes and stared off into the plain we had just crossed.

"Billy-boy," she said to me in a strange voice, "look down there and tell me what you see."

I followed the direction of her hand and a shock went through me from head to foot. Down there, slowly toiling across the sand, advanced a party of four persons. In the lead was a little old lady in a black dress. Behind her strode a grizzled Earth man in a flop-brimmed hat, another Earth man, and a Martian.

Detail for detail they were a duplicate of ourselves!

"A mirage!" said Ezra Karn.

But it wasn't a mirage. As the party came closer, we could see that their lips were moving, and their voices became audible. I listened in awe. The duplicate of myself was talking to the duplicate of Grannie Annie, and she was replying in the most natural way.

Steadily the four travelers approached. Then, when a dozen yards away, they suddenly faded like a negative exposed to light and disappeared.

"What do you make of it?" I said in a hushed voice.

Grannie shook her head. "Might be a form of mass hypnosis superinduced by some chemical radiations," she replied. "Whatever it is, we'd better watch our step. There's no telling what might lie ahead."

We walked after that with taut nerves and watchful eyes, but we saw no repetition of the "mirage." The wind continued to blow ceaselessly, and the sand seemed to grow more and more powdery.

For some time I had fixed my gaze on a dot in the sky which I supposed to be a high-flying cockatoo. As that dot continued to move across the heavens in a single direction, I called Grannie's attention to it.

"It's a kite," she nodded. "There should be a car attached to it somewhere."

She offered no further explanation, but a quarter of an hour later as we topped another rise a curious elliptical car with a long slanting windscreen came into view. Attached to its hood was a taut wire which slanted up into the sky to connect with the kite.

A man was driving and when he saw us, he waved. Five minutes later Grannie was shaking his hand vigorously and mumbling introductions.

"This is Jimmy Baker," she said. "He manages Larynx Incorporated, and he's the real reason we're here."

I decided I liked Baker the moment I saw him. In his middle thirties, he was tall and lean, with pleasant blue eyes which even his sand goggles could not conceal.

"I can't tell you how glad I am you're here, Grannie," he said. "If anybody can help me, you can."

Grannie's eyes glittered. "Trouble with the mine laborers?" she questioned.

Jimmy Baker nodded. He told his story over the roar of the wind as we headed back across the desert. Occasionally he touched a stud on an electric windlass to which the kite wire was attached. Apparently these adjustments moved planes or fins on the kite and accounted for the car's ability to move in any direction.

"If I weren't a realist, I'd say that Larynx Incorporated has been bewitched," he began slowly. "We pay our men high wages and give them excellent living conditions with a vacation on Callisto every year. Up until a short time ago most of them were in excellent health and spirits. Then the Red Spot Fever got them."

"Red Spot Fever?" Grannie looked at him curiously.

Jimmy Baker nodded. "The first symptoms are a tendency to garrulousness on the part of the patient. Then they disappear."

He paused to make an adjustment of the windlass.

"They walk out into the Baldric," he continued, "and nothing can stop them. We tried following them, of course, but it was no go. As soon as they realize they're being followed, they stop. But the moment our eyes are turned, they give us the slip."

"But surely you must have some idea of where they go," Grannie said.

Baker lit a cigarette. "There's all kinds of rumors," he replied, "but none of them will hold water. By the way, there's a cockatoo eyrie ahead of us."

I followed his gaze and saw a curious structure suspended between a rude circle of flagpole trees. A strange web-like formation of translucent gauzy material, it was. Fully two hundred cockatoos were perched upon it. They watched us with their mild eyes as we passed, but they didn't move.

After that we were rolling up the driveway that led to the offices of Larynx Incorporated. As Jimmy Baker led the way up the inclined ramp, a door in the central building opened, and a man emerged. His face was drawn.

"Mr. Baker," he said breathlessly, "seventy-five workers at Shaft Four have headed out into the Baldric."

Baker dropped his cigarette and ground his heel on it savagely.

"Shaft Four, eh?" he repeated. "That's our principal mine. If the fever spreads there, I'm licked."

He motioned us into his office and strode across to a desk. Silent Xartal, the Martian illustrator, took a chair in a corner and got his notebook out, sketching the room's interior. Grannie Annie remained standing.

Presently the old lady walked across to the desk and helped herself to the bottle of Martian whiskey there.

"There must be ways of stopping this," she said. "Have you called in any physicians? Why don't you call an enforced vacation and send the men away until the plague has died down?"

Baker shook his head. "Three doctors from Callisto were here last month. They were as much at loss as I am. As for sending the men away, I may have to do that, but when I do, it means quits. Our company is chartered with Spacolonial, and you know what that means. Failure to produce during a period of thirty days or more, and you lose all rights."

A visiphone bell sounded, and Baker walked across to the instrument. A man's face formed in the vision plate. Baker listened, said "Okay" and threw off the switch.

"The entire crew of Shaft Four have gone out into the Baldric," he said slowly. There was a large map hanging on the wall back of Baker's desk. Grannie Annie walked across to it and began to study its markings.

"Shaft Four is at the outer edge of the Baldric at a point where that corridor is at its widest," she said.

Baker looked up. "That's right. We only began operations there a comparatively short time ago. Struck a rich vein of Acoustix that runs deep in. If that vein holds out, we'll double the output of Interstellar Voice, our rival, in a year."

Grannie nodded. "I think you and I and Xartal had better take a run up there," she said. "But first I want to see your laboratory."

There was no refusing her. Jimmy Baker led the way down to a lower level where a huge laboratory and experimental shop ran the length of the building. Grannie seized a light weight carry-case and began dropping articles into it. A pontocated glass lens, three or four Wellington radite bulbs, each with a spectroscopic filament, a small dynamo that would operate on a kite windlass, and a quantity of wire and other items.

The kite car was brought out again, and the old woman, Baker and the Martian took their places in it. Then Jimmy waved, and the car began to roll down the ramp.

Not until they had vanished in the desert haze did I sense the loneliness of this outpost. With that loneliness came a sudden sense of foreboding. Had I been a fool to let Grannie go? I thought of her, an old woman who should be in a rocking chair, knitting socks. If anything happened to Annabella C. Flowers, I would never forgive myself and neither would her millions of readers.

Ezra Karn and I went back into the office. The old prospector chuckled.

"Dang human dynamo. Got more energy than a runaway comet."

A connecting door on the far side of the office opened onto a long corridor which ended at a staircase.

"Let's look around," I said.

We passed down the corridor and climbed the staircase to the second floor. Here were the general offices of Larynx Incorporated, and through glass doors I could see clerks busy with counting machines and report tapes. In another chamber the extremely light Acoustix ore was being packed into big cases and marked for shipment. At the far end a door to a small room stood open. Inside a young man was tilted back in a swivel chair before a complicated instrument panel.

"C'mon in," he said, seeing us. "If you want a look at your friends, here they are."

He flicked a stud, and the entire wall above the panel underwent a slow change of colors. Those colors whirled kaleidescopically, then coalesced into a three-dimensional scene.

It was a scene of a rapidly unfolding desert country as seen from the rear of a kite car. Directly behind the windscreen, backs turned to me, were Jimmy Baker, Grannie, and Xartal. It was as if I were standing directly behind them.

"It's Mr. Baker's own invention," the operator said. "An improvement on the visiphone."

"Do you mean to say you can follow the movements of that car and its passengers wherever it goes? Can you hear them talk too?"

"Sure." The operator turned another dial, and Grannie's falsetto voice entered the room. It stopped abruptly. "The machine uses a lot of power," the operator said, "and as yet we haven't got much."

The cloud of anxiety which had wrapped itself about me disappeared somewhat as I viewed this device. At least I could now keep myself posted of Grannie's movements.

Karn and I went down to the commissary where we ate our supper. When we returned to Jimmy Baker's office, the visiphone bell was ringing. I went over to it and turned it on, and to my surprise the face of Antlers Park flashed on the screen.

"Hello," he said in his friendly way. "I see you arrived all right. Is Miss Flowers there?"

"Miss Flowers left with Mr. Baker for Shaft Four," I said. "There's trouble up there. Red spot fever."

"Fever, eh?" repeated Park. "That's a shame. Is there anything I can do?"

"Tell me," I said, "has your company had any trouble with this plague?"

"A little. But up until yesterday the fever's been confined to the other side of the Baldric. We had one partial case, but my chemists gave the chap an antitoxin that seems to have worked. Come to think of it, I might drive over to Shaft Four and give Jimmy Baker the formula. I haven't been out in the Baldric for years, but if you didn't have any trouble, I shouldn't either."

We exchanged a few more pleasantries, and then he rang off. In exactly an hour I went upstairs to the visiscreen room.

Then once more I was directly behind my friends, listening in on their conversation. The view through the windscreen showed an irregular array of flagpole trees, with the sky dotted by high-flying cockatoos.

"There's an eyrie over there," Jimmy Baker was saying. "We might as well camp beside it."

Moments later a rude circle of flagpole trees loomed ahead. Across the top of them was stretched a translucent web. Jimmy and Grannie got out of the car and began making camp. Xartal remained in his seat. He was drawing pictures on large pieces of pasteboard, and as I stood there in the visiscreen room, I watched him.

There was no doubt about it, the Martian was clever. He would make a few rapid lines on one of the pasteboards, rub it a little to get the proper shading and then go on to the next. In swift rotation likenesses of Ezra Karn, of myself, of Jimmy Baker, and of Antlers Park took form.

Ezra spoke over my shoulder. "He's doing scenes for Grannie's new book," he said. "The old lady figures on using the events here for a plot. Look at that damned nosy bird!"

A silver cockatoo had alighted on the kite car and was surveying curiously Xartal's work. As each drawing was completed, the bird scanned it with rapt attention. Abruptly it flew to the top of the eyrie, where it seemed to be having a consultation with its bird companions.

And then abruptly it happened. The cockatoos took off in mass flight. A group of Earth people suddenly materialized on the eyrie, talking and moving about as if it were the most natural thing in the world.

With a shock I saw the likeness of myself; I saw Ezra Karn; and I saw the image of Jimmy Baker.

The real Jimmy Baker stood next to Grannie, staring up at this incredible mirage. Grannie let out a whoop. "I've got it!" she said. "Those things we see up there are nothing more than mental images. They're Xartal's drawings!"

"Don't you see," the lady continued. "Everything that Xartal put on paper has been seen by one or more of these cockatoos. The cockatoos are like Earth parrots all right, but not only have they the power of copying speech, they also have the ability to recreate a mental image of what they have seen. In other words their brains form a powerful photographic impression of the object. That impression is then transmitted simultaneously in telepathic wavelengths to common foci. That eyrie might be likened to a cinema screen, receiving brain vibrations from a hundred different sources that blend into the light field to form what are apparently three-dimensional images."

The Larynx manager nodded slowly. "I see," he said. "But why don't the birds reconstruct images from the actual person. Why use drawings?"

"Probably because the drawings are exaggerated in certain details and made a greater impression on their brains," Grannie replied.

Up on the eyrie a strange performance was taking place. The duplicate of Grannie Annie was bowing to the duplicate of Jimmy Baker, and the image of Ezra Karn was playing leap frog with the image of Antlers Park.

Then abruptly the screen before me blurred and went blank.

"Sorry," the operator said. "I've used too much power already. Have to give the generators a chance to build it up again."

Nodding, I turned and motioned to Karn. We went back downstairs.

"That explains something at any rate," the old prospector said. "But how about that Red spot fever?"

On Jimmy Baker's desk was a large file marked: FEVER VICTIMS. I opened it and found it contained the case histories of those men who had been attacked by the strange malady.

Reading them over, I was struck by one detail. Each patient had received the first symptoms, not while working in the mines, but while sleeping or lounging in the barracks.

Five minutes later Karn and I were striding down a white ramp that led to the nearest barracks. The building came into sight, a low rectangular structure, dome-roofed to withstand the violent winds.

Inside double tiers of bunks stretched along either wall. In those bunks some thirty men lay sleeping.

The far wall was taken up by a huge window of denvo-quartz. As I stood there, something suddenly caught Ezra Karn's eye. He began to walk toward that window.

"Look here," he said.

Six feet up on that window a small almost imperceptible button of dull metal had been wedged into an aperture cut in the quartz. The central part of the button appeared to be a powerful lens of some kind, and as I seized it and pulled it loose, I felt the hum of tiny clock work.

All at once I had it! Red spot fever. Heat fever from the infra-red rays of Jupiter's great spot. Someone had constructed this lens to concentrate and amplify the power of those rays. The internal clockwork served a double purpose. It opened a shutter, and it rotated the lens slowly so that it played for a time on each of the sleeping men.

I slid the metal button in my pocket and left the barracks at a run. Back in the visiscreen room, I snapped to the operator:

"Turn it on!"

The kite car swam into view in the screen above the instrument panel. I stared with open eyes. Jimmy Baker no longer was in the car, nor was Xartal, the Martian. Grannie Annie was there, but seated at the controls was Antlers Park, the manager of Interstellar Voice.

Ezra Karn jabbed my elbow. "Grannie's coming back. I thought she'd be getting sick of this blamed moon."

It didn't make sense. In all the years I'd known Annabella C. Flowers, never yet had I seen her desert a case until she had woven the clues and facts to a logical conclusion.

"Ezra," I said, "we're going to drive out and meet them. There's something screwy here."

Ten minutes later in another kite car we were driving at a fast clip through the powdery sands of the Baldric. And before long we saw another car approaching.

It was Grannie. As the car drew up alongside I saw her sitting in her prim way next to Antlers Park. Park said:

"We left the others at the mine. Miss Flowers is going back with me to my offices to help me improve the formula for that new antitoxin."

He waved his hand, and the car moved off. I watched it as it sped across the desert, and a growing suspicion began to form in my mind. Then, like a knife thrust, the truth struck me.

"Ezra!" I yelled, swinging the car. "That wasn't Grannie! That was one of those damned cockatoo images. We've got to catch him."

The other car was some distance ahead now. Park looked back and saw us following. He did something to the kite wire, and his car leaped ahead.

I threw the speed indicator hard over. Our kite was a huge box affair with a steady powerful pull to the connecting wire. Park's vehicle was drawn by a flat triangular kite that dove and fluttered with each variance of the wind. Steadily we began to close in.

The manager of Interstellar Voice turned again, and something glinted in his hand. There was a flash of purple flame, and a round hole appeared in our windscreen inches above Karn's head.

"Heat gun!" Ezra yelled.

Now we were rocketing over the sand dunes, winding in and out between the flagpole trees. I had to catch that car I told myself. Grannie Annie's very life might be at stake, not to mention the lives of hundreds of mine workers. Again Park took aim and again a hole shattered our windscreen.

The wind shifted and blew from another quarter. The box kite soared, but the triangular kite faltered. Taking advantage of Park's loss of speed, I raced alongside.

The I. V. manager lifted his weapon frantically. But before he could use it a third time, Ezra Karn had whipped a lariat from his belt and sent it coiling across the intervening space.

The thong yanked tight about the manager's throat. Park did the only thing he could do. He shut off power, and the two cars coasted to a halt. Then I was across in the other seat, wrenching the weapon free from his grasp.

"What have you done with Miss Flowers?" I demanded.

The manager's eyes glittered with fear as he saw my finger tense on the trigger. Weakly he lifted an arm and pointed to the northwest.

"Val-ley. Thir-ty miles. Entrance hidden by wall of ... flagpole trees."

I leaped into the driver's seat and gave the kite its head. And now the country began to undergo a subtle change. The trees seemed to group themselves in a long flanking corridor in a northwesterly direction, as if to hide some secret that lay beyond. Twice I attempted to penetrate that wall, only to find my way blocked by those curious growths.

Then a corridor opened before me; a mile forward and the desert began again. But it was a new desert this time: the sand packed hard as granite, the way ahead utterly devoid of vegetation. In the distance black bulging hills extended to right and left, with a narrow chasm or doorway between.

I headed for that entrance, and when I reached it, I shut off power with an exclamation of astonishment.

There was a huge chair-shaped rock there, and seated upon it was Grannie Annie. She had a tablet in her hands, and she was writing.

"Grannie!" I yelled. "What're you doing here? Where's Mr. Baker?"

She rose to her feet and clambered down the rock.

"Getting back Jimmy's mine laborers," she said, a twinkle in her eyes. "I see you've got Antlers Park. I'm glad of that. It saves me a lot of trouble." She took off her spectacles and wiped them on her sleeve. "Don't look so fuddled, Billy-boy. Come along, and I'll show you."

She led the way through the narrow passage into the valley. A deep gorge, it was, with the black sheer cliffs on either side pressing close. Ten feet forward, I stopped short, staring in amazement.

Advancing toward me like a column of infantry came a long line of Larynx miners. They walked slowly, looking straight ahead, moving down the center of the gorge toward the entrance.

But there was more! A kite car was drawn up to the side. The windscreen had been removed, and mounted on the hood was a large bullet-like contrivance that looked not unlike a search lamp. A blinding shaft of bluish radiance spewed from its open end. Playing it back and forth upon the marching men were Jimmy Baker and Xartal, the Martian.

"Ultra violet," Grannie Annie explained. "The opposite end of the vibratory scale and the only thing that will combat the infra-red rays that cause red spot fever. Those men won't stop walking until they've reached Shaft Four."

Grannie Annie told her story during the long ride back to Shaft Four. We drove slowly, keeping the line of marching Larynx miners always ahead of us.

Jimmy Baker had struck a new big lode of Acoustix, a lode which if worked successfully would see Larynx Incorporated become a far more powerful exporting concern than Interstellar Voice. Antlers Park didn't want that.

It was he or his agents who placed those lens buttons in the Larynx barracks. For he knew that just as Jupiter's great spot was responsible for a climate and atmosphere suitable for an Earthman on this Eighth Moon, so also was that spot a deadly power in itself, capable when its rays were concentrated of causing a fatal sickness.

Then suddenly becoming fearful of Grannie's prying, Antlers Park strove to head her off before she reached Shaft Four.

He did head her off and managed to lure her and Baker and Xartal into the Shaft barracks where they would be exposed to the rays from the lens button. But Grannie only pretended to contract the plague.

Park then attempted to outwit Ezra Karn and me by returning in Jimmy Baker's kite car with a cockatoo image of Grannie.

I listened to all this in silence. "But," I said when she had finished, "how did Park manage to have that image created and why did the mine laborers walk out into the Baldric when they contracted the fever?"

Grannie Annie frowned. "I'm not sure I can answer the first of those questions," she replied. "You must remember Antlers Park has been on this moon five years and during that time he must have acquainted himself with many of its secrets. Probably he learned long ago just what to do to make a cockatoo create a mental image.

"As for the men going out into the Baldric, that was more of Park's diabolical work. In the walls of the barracks besides those lens buttons were also miniature electro-hypnotic plates, with the master controlling unit located in that valley. Park knew that when the miners were in a drugged condition from the effects of the fever they would be susceptible to the machine's lure.... And now, Billy-boy, are you coming with me?"

"Coming with you?" I repeated. "Where?"

The old lady lit a cigarette. "Pluto maybe," she said. "There's a penal colony there, you know, and that ought to tie in nicely with a new crime story. I can see it now ... prison break, stolen rocket ship, fugitives lurking in the interplanetary lanes...."

"Grannie," I laughed. "You're incorrigible!"