Twice that night the two young men had seen the thing, and their hour for turning in had long since passed as they lay half reclining on the ground by their campfire waiting, hoping that it would return once more. Their interest in the strange visitant had completely banished all sensations of fatigue from a full day of vacation fishing in the cold Adirondack streams among which they were camping for that month.

They had discussed the appearance until there was nothing more they could say; and now as for the last hour, they watched in silence, only moving to knock the dottle from their pipes and to get fresh lights off the splinters they stuck into their slumbering fire. The velvet night was now at full reign, and the myriad stars in their familiar patterns leaned close--brilliant jewels for man to share but never pluck.

Jim Wilson had seen the thing first--a pinpoint of cherry red that moved upward in a perfect arc against the brilliant white constellations of the east. As it rose, it grew perceptibly larger, to dwindle again as it arced over the western horizon.

Nearly an hour later it had appeared again; but this time, when halfway up the skies, it had changed its direction until it was heading directly over the spot where the two thrilled campers were watching; and as it approached they saw its color fade slowly until it had disappeared completely from sight among the inky patches between the stars overhead. For minutes the two were not able to locate it--until Jim, once again, had pointed to a faint red spot that grew in color and intensity as it drew away from the zenith. Once again it had disappeared over the rim of the western world--and from then on there was no thought of sleep in the minds of Jim Wilson and Clee Partridge. They were watching the skies, hoping it would return.

“What was the thing?” Jim Wilson exclaimed suddenly with exasperation. “I’ve been racking my brain, Clee, but nothing I can think of makes sense. It couldn’t have been a plane, and it couldn’t have been a meteor. And if it was a fire-fly--well, then I’m one too.” He paused, and looked at the other. “Any new suggestions?” he asked.

“Me--I still think it was a space ship from Mars or Venus,” Clee Partridge answered drily; “searching for a couple of good Earth-men to help ‘em out of some jam. You noticed the way it disappeared for a moment when it was overhead: it was looking us over.”

“Then it’ll be back,” answered Jim, not to be outdone, “for it’s not apt to find anyone better qualified. I, myself, would kinda like to take a joy-ride out through the Great Dipper.”

Clee smiled and looked down at the luminous dial of his wrist watch. The two resumed their vigil, and there was quietness between them. For some time they lost themselves in the sparkling glory of the firmament, hardly moving, except to pull closer the collars of their flannel shirts against the increasing coldness of the mountain air.

And then for the third time that night the mysterious sky traveler sprang over the trees on the eastern horizon. Suddenly it appeared; both men saw it at once; and this time it made a clear, beautiful arc straight for the zenith. As it raised, it grew in size, a beautiful, delicate cherry star spanning the whole welkin. The two men got to their knees and watched it, breathless with fascination.

“Look!” cried Jim suddenly.

As had happened on its second appearance, the thing began to slow up and its color gradually faded as it drew directly overhead. By the time it should have reached the zenith it could no longer be seen. It had dissolved against the inky spaces above.

“It should come into view again in a moment,” Clee said; “a little farther on, like the other time.”

They watched, thrilled by the mystery of the midnight phenomenon. Minutes passed, but still it did not appear. Clee grew restive, and as his eyes chanced on his wrist watch he started violently and held out his arm for Jim to see. The radium-painted hands and dial were glowing with unusual brilliance.

Looking quickly into the skies again, Clee sensed something wrong; something different. For a moment he could not figure out what--and then it came to him. One of the great stars, one that he had been watching in its climb up the sky through the night, had disappeared!

He got excitedly to his feet, grabbed his companion’s arm and pointed out this strange thing--and as he pointed another star blinked out and did not reappear.

“Something’s happening up there,” Jim said soberly. “I don’t know what; but I, for one, don’t feel quite comfortable.”

He kept peering at the place pointed out, at a spot of black even darker than the inky sky; or did he only imagine it was darker? he asked himself. Soon the spot enlarged; became a distinct patch; then, growing still, obliterated one star after another around its borders. It made a pure circle; and before long the starlight glinting off its sides showed it to be a great, tinted sphere.

Swiftly it dropped down on the two men, and they watched it hypnotized, incapable of moving. It was only a hundred yards overhead when some presence of mind returned to Clee.

“Run, Jim!” he yelled, moving away. “It’s coming straight down!”

Wilson came out of his daze and the two sprinted wildly for the path that led down the spur on which their camp was located. They had not made more than fifty yards when they heard a dull thud, and, turning, saw the great sphere resting on the ground with a slight rocking motion that quickly ceased.

A gully cut into the trail ahead, and when they reached it Clee grabbed his partner’s arm and pulled him off to one side, where, panting with their sudden exertion, they wormed up to the brow and peeped over at their strange visitor.

The sphere stood in the starlight on the very spot they had been occupying when they first saw it. Right in their campfire it lay--a great, dark-red crystal shape perhaps fifty feet in diameter, whose surface sparkled with innumerable facets. It rested quietly on the ground, as if oblivious of the two routed men breathlessly watching it from a short distance. No ports or variations of any kind were visible to mar its star-reflecting sides.

“It must be some new kind of dirigible!” murmured Jim; “but why did it go and pick on us for its midnight call!”

“It’s a space ship from Mars,” answered Clee with a serious face. “They heard you, and’re coming to take you for your ride. See?” he added quickly, pointing.

A large door was opening in the side of the sphere, and the illumination within threw a bright beam of amber-colored light in their direction. A metallic ramp slid out and angled down to the ground.

Breathlessly the two men waited to see who would emerge, but a long time went by without their catching the slightest sign of life within. The face of Clee’s wrist watch was fluorescing brilliantly now, and moment by moment the weird glow was increasing. Jim stirred nervously.

“I don’t mind telling you, I’m scared,” he said.

“Aw, they won’t make you walk back,” consoled Clee; but he was scared himself. Why didn’t something happen? Why didn’t someone come out of the ship?

Jim thought he heard a noise, and touched Clee on the shoulder, pointing to a place on the trail down which they had come a few minutes before. Clee looked, and as he did so the hair on the back of his neck stood up. For the bushes along the side of the path were moving as if they were being brushed aside by someone in passing--someone making a straight line to the spot where they lay concealed. And no one was there!

“Can they be invisible?” breathed Jim, every pore in his body prickling.

For a moment the two men could hardly breathe, so great was their unnamed fear. During that time no other movements could be noted. Then Clee suddenly pointed to a bush only five yards away. Half a dozen leaf-tipped branches were bending slowly in their direction--and then a sharp crack, as of a broken twig, came to them from the same spot.

Panic, blind and unreasoning, swept them. “Run!” gasped Jim; and together, instinctively, they turned and scrambled down the side of the ridge to get away, anywhere, far from the approaching menace of they knew not what. Reckless of possible injury, they slid and stumbled down the brush-covered slope--and right behind them came sudden crashing sounds of pursuit.

New fears lent wings to their flight, but the sounds behind continued inexorably at their heels no matter how fast they ran or how lucky they were in making past obstacles. Their pursuer was as fast as they. They had no idea who--or what--it might be, for in the brief glances they snatched over their shoulders they could not see anything at all!

The going was bad, and the two campers had not gone more than a quarter-mile when they were breathing hard, and felt that they could not make one more step without collapsing on the ground to give their laboring lungs a chance to catch up. Panting like dogs they dragged themselves along through pine and birch trees, around large rocks and over briar-covered hills, only a few steps ahead of their pursuer.

Then Partridge, a little in the lead as they made their way up a steep slope, heard Jim suddenly go sprawling; heard him gasp:

“It’s got me!”

Turning, he saw his partner rolling and threshing violently on the ground, and now and then lashing out at the empty air with his fists. Without a moment’s hesitation he jumped from his position above--jumped square and hard into the space which Jim’s invisible assailant should be occupying. With a great thud he crashed into some unseen body in the air, and went down, the breath knocked out of him. As he got to his knees an odor like that of cloves came to his nostrils, and something caught him around the neck and began constricting. Frantically he tried to tear himself loose, but the harder he struggled the more strangling became the grip on his neck; and at last, faint from the growing odor and the lack of air, his efforts dwindled into a spasmodic tightening and relaxing of the muscles.

Then, for a moment, the hold on his neck must have loosened, for he found himself able to breathe a little. Turning, he saw Jim at his side, apparently similarly held.

“If I could only--see it!” Clee managed to get out. Jim’s spasmodic, bitter answer came a moment later.

“Being invisible--tremendous advantage!” he gasped.

In desperation the two men again began to fight against the clutches that were holding them, and this time the grip about their necks unexpectedly loosened--to bring to their noses the odor of cloves overpowering in strength. And that was all they knew before they lapsed into a black and bottomless void...

Through the lifting haze of returning consciousness Clee felt a command to get up. As he automatically complied he saw that Jim was doing likewise. Once on his feet he felt another impulse to go to the cherry-crystal sphere, visible in the distance; but his legs were weak, and neither he nor Jim could walk very well until out of the nothingness around them came something of invisible bulk to lend them support.

Slowly, carefully, straight for the waiting globe the two men were conducted; and in his state of half-consciousness Clee wondered at the impotence of his will to make his body offer resistance. They passed right by their tent and up the ramp to the inside of the strange sphere.

Clee’s impressions were blurred and dull, but he noticed that they were in a small room brilliant with amber light, on one wall of which there was a circular area which contained a dozen or more instruments and levers and wheels. As his eyes rested on them, one of the levers moved, seemingly of itself, and the ramp came sliding into the ship and the thick door slowly swung closed. Then they were conducted along a short, narrow passageway into which opened, on the right, a small dim room; and there the grip about their bodies loosened and they slumped to the floor. The door whereby they had entered, closed.

A faint vibration became noticeable; they suddenly felt very heavy; and to the accompaniment of a low but rising hum they saw one wall of their room begin to glow with a beautiful cherry color. Although they had been too stupefied to try to speak, this spurred their tired bodies, and they dragged themselves over to it. They found the wall to be of some kind of hard crystal; it was the outer shell of the sphere; and it now gleamed redly transparent.

Far out and down the men saw a great convex surface on which lay narrow ribbons of silver, winding veinlike through dark areas that were in some places lit by little clusters of twinkling lights. As they watched, the distances on the surface shrank in on themselves; they could see the outline of a great circle. The sight stimulated the exhausted men. In a hushed and awestruck voice, Jim Wilson broke the silence.

“We’ve been kidnaped,” he said. “Being taken God knows where, out among the stars...”

He was getting the sky-ride he had asked for.

Clee smiled faintly, and was going to remind him of this; but he was too tired to make the effort. He only looked at the tremendous scene below: at the Earth they knew so well, with its familiar streets, comfortable fireplaces, the faces of those they loved and those others who were their friends...

The Earth soon became a ball--a globe such as he had used at school, showing clearly the outline of the continents and oceans. And little by little it dwindled, until it was only a ghostly shape far out in nothingness...

A little later, had the two Earthlings not been deep in sleep, they might have seen enter a strange-looking man clad in odd garments--a man whose great, bulging head was quite bald, and whose wrinkled, leprous-white face wore an expression of unutterable wisdom and majesty. In his hands he carried a strange piece of apparatus which he held to Jim’s wrist while it emitted a coarse vibratory hum that whined slowly up in pitch until it passed the range of hearing. He did the same thing to Clee, and then he quietly left.

But the two Earthlings knew nothing of this. Limp on the floor, oblivious to everything, they slept...

Some hours later found the kidnapped men well recovered and sitting on the floor of their cell talking over their situation. As usual, Wilson was thinking out loud.

“What can they be?--or who?” he asked, frowning with his thought. “They can’t be from Earth, for no one there could invent such a ship as this and keep it a secret; and even if someone had, he could never have done the equally astounding thing of inventing a way to render living bodies invisible. I doubt if the thing that caught us was human, by what I was able to feel in my short struggle with it. There was something that might have been a hand; but the strength and the weight of its body was enormous!”

“Well, we’ll probably soon see,” commented Clee with philosophic resignation and pulling out of a hip pocket a package of tobacco and his corn-cob pipe. “Or, rather, we may soon know. Our captors may keep themselves invisible; and of course it’s barely possible that it’s their natural state to be invisible, so that we may never hope to see them. What I’m chiefly afraid of, is that they are from some other planet, and that that’s where we are being taken--though heaven knows what any creatures so infinitely far ahead of us Earthlings scientifically could want with a pair of young Earth lawyers!”

He offered the package to Jim. “Here, have a smoke; you’ll feel better,” he said. “While there’s tobacco there’s hope.”

“At least they don’t seem disposed to kill us right off,” returned Jim, handing back the tobacco after lighting his own pipe. “Later--if there’s to be any ‘later’ for us--we may be able to find a way to get out of this room; though how we’d run the ship, to get back home, is another hard brick wall ... Maybe the controls are invisible, too!” he suggested with a wry grin. “Ever take any pre-law courses on how to work the invisible controls of a space ship?”

Clee’s reply was spoken low, and was entirely irrelevant.

“That’s funny,” he said.

He was looking at the face of the watch on his left wrist. For the first time since they had been abducted, its abnormal brightness had left it.

As Jim watched, inquiringly, Clee moved his right hand a little, and once more the dial leaped out through the dimness with unnatural brilliance. Jim saw that his friend was holding in this hand the package of tobacco. Clee repeated the demonstration.

“The dial glows with unusual brightness always--except when I hold the package of tobacco in front of it at this spot,” he said wonderingly, half to himself. “If I remember my science right, ultra-violet light would make the radium on the dial glow; and the lead in the tin-foil of the tobacco wrapping would screen it off. Let’s see--”

He crossed to the other side of the room and held his watch and the package of tobacco in various positions until he again found one line along which the watch-dial gave off only its customary light.

“Yes,” he said, “--exactly in the extended line made by my watch and this package of tobacco is the source of the ray which makes the watch-dial glow. It’s probably the control room of this ship.”

“An extraordinary deduction, my dear Sherlock,” commented Wilson drily; “and valuable. I wish you’d now take a moment and deduce the reason for the mysterious appearance of the lumps on the back of our necks. I know I didn’t have mine before I was taken for this sky-ride.”

As he spoke, his hand sought the back of his neck where there was a fat lump about the size of a quarter--a lump not painful, for all its newness and size. Hard pushing with probing fingers had revealed something that seemed to be hard and flat, buried within; but close examinations failed to show any wound or scar, and the men had no notion what the lumps might be. Clee’s was just like Jim’s.

But Clee did not respond to his friend’s invitation. A heavy mood had come over him; he was standing by the outer wall, looking out. Jim went and stood beside him, his hand on his shoulder, and together they gazed through the cherry-crystal wall of their prison ship out on the loneliness of the immeasurable miles outside. For them, space was red, instead of the deep black they knew they would see through colorless glass. Brilliant pinpoints of light, millions of them, in all sizes, made up the infinite space that was the background of their adventure.

To which one--near which one were they going? Would they ever return to their Earth again? Would their friends ever know of the incredible adventure that had overtaken them?--or would they, after the few weeks of searching and inquiry that must follow their disappearance, at last conclude that some nameless mountain disaster had made them victims, and give them up for dead? No doubt. And month after succeeding month their memory would fade from the minds of those who had loved them, while they would be--where?...

A peculiar, dynamic thought came simultaneously into the minds of the two men. It was not a word: it seemed more like a feeling; but its unquestionable import was “Come.” Together they rose, and looked at each other wonderingly. Again came the feeling. They started for the door.

“But that’s foolish!” Jim said aloud, as if objecting to his own thought. “The door’s locked! We tried it!” He looked at Partridge, who returned his gaze blankly--and then, in spite of what he had said, he reached out and turned the latch.

The door swung open!

Expressions of surprise died on the men’s lips as again came the compelling urge to go to some unknown destination.

“Suggestion!” said Clee, as he passed through the doorway. “Someone’s suggesting--telepathically willing--that we come to him! And I--God help me--I can’t resist!”

His neck corded with veins and muscles with his effort to restrain his body from obeying the mysterious command that was drawing it onward. Wilson, one arm outstretched in a repelling gesture, his legs stiff and tight, was also trying to resist. But the will that had sounded within them was stronger than theirs, and slowly, inevitably, they were drawn down the passage.

Their carpeted way took them back to the entrance chamber and then up a steeply sloping corridor that led upward to the left. As they passed along they saw that the hand of a master had made on the walls, in panel effect, marvelously complicated decorations in many-colored mosaic. No man of Earth could ever have done such work, the two men realized--and this thought did not cheer them any.

At the top of their curving passage a doorway led them into a spacious room hung with soft, finely woven tapestries with a metallic lustre and furnished with deep-napped rugs and luxurious chairs and divans. Through this room the intangible threads of the alien will directed them--on into a wide-vaulted alcove about one-third its size. There, the strange clutch on them relaxed, and they looked about, at first apprehensively, then with growing boldness and curiosity.

“This is the control room!” exclaimed Clee suddenly; and after a moment Jim agreed with him. It was the simplicity of the controls which had prevented them from recognizing it at first. Against the left wall was a great table with a tilted top, bearing, in its center, a raised and hooded eyepiece giving a view into a large, enclosed black box. On each side were several rows of small, shiny, metallic levers and what they took to be instrument dials--round, cup-shaped depressions with pointers free to move across dials lined with disorderly and meaningless convolutions. For the full length of the middle wall, straight ahead, was a broad table of some jet-black polished material, and on it was a large array of instruments and apparatus, all unfamiliar to them. Against the draperies of the wall to their right was one large cushioned chair, simple and beautiful in its lines.

No living person or thing could be discerned in either the main room or the alcove.

For several minutes the two men walked all about, examining everything they saw with curiosity and interest; and then Clee discovered a peculiar thing. His watch-dial, glowing very brightly now, would perceptibly increase in brilliance every time he neared the great chair. With sudden inspiration he took out his package of tobacco and held it in the line his watch made with the chair--and he found that his watch stopped glowing. He tried it again from another angle, and the result was the same. From that chair came the electrical disturbance that was making his watch-dial glow--yet nowhere near the chair was any bit of electrical apparatus to be seen.

What he did see in the chair, though, almost caused his heart to stop beating. The cushions of the seat, compressed before, began to puff out to full volume, as if someone had just risen from them. And then, faintly but sharply outlined in the long-napped rug in front, appeared the print of a human shoe!

“A man!” breathed Clee. “A human being!”

The two men stood frozen in their tracks. Clee’s arm, with the package of tobacco in his hand, was still outstretched toward the great chair, but now the dial of his watch was glowing brightly again. Something within caused him in spite of his terror to move the package between the watch and the space above the footprint on the rug. The glowing stopped. The man--devil--whatever it was that made the print--was the source of the strange excitation!

This took but a second--the interval before another shoe-print formed in the rug in their direction. Jim gasped something unintelligible and started to back away; but no sooner did Partridge start to follow suit, than a compulsion to stand still came over them. Caught where they were, unable to move, they saw the shoe-prints come towards them. Slowly, step by step, twelve inches apart, they came, and did not stop until they were only four or five feet away.

“We’ll jump him, if we get the chance!” hissed Jim, never taking his eyes off the prints.

“Yes,” came the answer; but Clee’s further words were cut off in the making by an added compulsion to keep quiet. Were their words understood? The two men were locked, speechless, where they stood. And by some creature with a human footprint whom they could not see!

The touch of firm flesh came out of the nothingness of space about them, to poke and pry all over their bodies. Anger began to take the place of their fear, as, for some time, impotent of resistance, they had to submit to the examination given them. They were prodded and felt like dogs at a show; their breathing and heart action were carefully listened to; their mouths were opened and their teeth inspected as if they were horses offered for sale. Both men were inwardly fuming.

“Dogs!” shouted Clee in his thoughts. “Treating us like dogs, to see how healthy we are! Does he want us for slaves?”

At last the examination came to a stop, and they saw the shoe-prints in the rug go over to the black table and remain there, heels toward them, while various pieces of apparatus were invisibly moved across the table top. For a moment the compelling will did not seem, to Clee, to be constraining him as much is it had, and he began to wonder if he might not have a little control over his body again. Tentatively he tried to break through the oppressing blanket of foreign will; his arms and legs moved a little; he succeeded! He caught Jim’s eye and showed him. He thrilled all over at his discovery, and his will to move measurably increased with his growing confidence that he could.

The toes of the prints were still turned away. He was going to try and get the man or monster who was making them.

He gestured to Jim, and with a great effort took a step in the invisible man’s direction. A thrill of gladness helped him on--for Jim was following suit!

Again and again, with greatest mental effort, they made steps toward the footprints, which, remaining side by side and motionless, gave them increasing hope of stealing up unobserved. When they were only three feet away Clee motioned to Jim, and with a tremendous effort of will they jumped at the space where their enemy should be.

They hit him hard, and bore him heavily to the floor. By the feel, he was a man such as they! Clee’s blood leaped with the lust for revenge, and blanking his mind against strong urges to cease his attack he rained savage blows at the place he was holding.

But almost at once they had evidence that their opponent was not such a man as they. A terrific pain stabbed suddenly through them, and they doubled up on the floor, writhing in agony. It was as if every nerve in their bodies had turned into white-hot wire, and was searing through their flesh. Again and again came the terrible stabs of pain--and their source seemed to be the mysterious lumps at the back of their necks!

At last they ceased coming, and Jim and Clee stretched out on the floor all but unconscious from the terrific shocks of fiery agony. They were completely helpless; further thoughts of resistance were unthinkable. But they were not left lying long. There came a telepathic compulsion to stand up; and they found themselves obeying, in spite of the shrieking protest of their every nerve.

Twitching, stumbling, they were made to do servile things--to kneel on the floor; get up again; turn round and round; bow low, then stretch backwards. And out of the air around them came shocking blows which landed on their faces, necks and chests; feet which kicked out at their shins; and they had to stand there and take it, helpless to resist.

Then Clee, as the nearer of the two men, was pushed over to the work-table, where an oval head-piece of finely-woven wire was fitted over his head. Another very large one, standing next to it, and connected to it by wires which led to a small instrument panel nearby, lifted into the air until it must have settled about the head of their persecutor. A dial on the panel turned slowly. And gradually the helmet resting in the air dissolved into nothingness before their eyes.

A slight nausea swept over Clee as it did so, and in the midst of it he felt a series of sharp, staccato thoughts--thoughts which did not seem to be composed of words, and yet were clear and intelligible.

“Fool of a fool!” crackled in his brain with almost a physical effort, “do you think to resist Xantra? Do you think with your sub-human minds to overcome one of the Tillas, Masters of the Universe? Close you were to death--and death indeed would have come had I not other plans for you.

“Know that henceforth you and your companion are my slaves. You will jump at my slightest will; serve me as best you can with such intelligence as you may possess. For faithful, willing service you shall have food and clothing and a portion of leisure. Disobedience and tardiness will bring you the pain you have already tasted; revolt, or the attempt to escape--death; but only after torture such as you have never known.

“I shall never repeat this mode of communication: it is as physically nauseating to me as to you. And you may never expect to see me, though I can always see you. By vibrational means I have given you the universal atomic rhythm of all Tillian slaves; and, although in that state your fellow-slaves will be visible to you, I, your master, will not!