It was August 19, 2037. The United Nations was just fifty years old.

Televisors were still monochromatic. The Nidics had just won the World Series in Prague. Com-Pub observatories were publishing elaborate figures on moving specks in space which they considered to be Martian spaceships on their way to Earth, but which United Nations astronomers could not discover at all. Women were using gilt lipsticks that year.

Heat-induction motors were still considered efficient prime movers.

Thorn Hard was a high-level flier for the Pacific Watch. Bathyletis was the most prominent of nationally advertised diseases, and was to be cured by RO-17, “The Foundation of Personal Charm.” Somebody named Nirdlinger was President of the United Nations, and somebody else named Krassin was Commissar of Commissars for the Com-Pubs. Newspapers were printing flat pictures in three colors only, and deploring the high cost of stereoscopic plates. And ... Thorn Hard was a high-level flier for the Pacific Watch.

That is the essential point, of course--Thorn Hard’s work with the Watch. His job was, officially, hanging somewhere above the twenty-thousand-foot level with his detector-screens out, listening for unauthorized traffic. And, the normal state of affairs between the Com-Pubs and the United Nations being one of highly armed truce,

“unauthorized traffic” meant nothing more or less than spies.

But on August 19th, 2037, Thorn Hard was off duty. Decidedly so. He was sitting on top of Mount Wendel, in the Rockies; he had a ravishingly pretty girl sitting on the same rock with him, and he was looking at the sunset. The plane behind him was an official Watch plane, which civilians are never supposed to catch a glimpse of. It had brought Thorn Hard and Sylva West to this spot. It waited now, half-hidden by a spur of age-eroded rock, to take them back to civilization again. Its G.C. (General Communication) phone muttered occasionally like the voice of conscience.

The colors of the mountain changed and blended. The sky to westward was a glory of a myriad colors. Man and girl, high above the world, sat with the rosy glow of dying sunlight in their faces and watched the colors fade and shift into other colors and patterns even more exquisite. Their hands touched. They looked at each other. They smiled queerly, as people smile who are in love or otherwise not quite sane. They moved inevitably closer...

And then the G.C. phone barked raucously:

“All Watch planes attention! Urgent! Extreme high-level traffic reported seven-ten line bound due east, speed over one thousand. All Watch planes put out all detectors and use extra vigilance. Note: the speed, course, and time of report of this traffic checks with Com-Pub observations of moving objects approaching Earth from Mars. This possibility should be considered before opening fire.”

Thorn Hard stiffened all over. He got up and swung down to the stubby little ship with its gossamer-like wings of cellate. He touched the report button.

“Plane 257-A reporting seven-ten line. Thorn Hard flying. On Mount Wendel, on leave. Orders?”

He was throwing on the screens even as he reported. And the vertical detector began to whistle shrilly. His eyes darted to the dial, and he spoke again.

“Added report. Detector shows traffic approaching, bound due east, seven hundred miles an hour, high altitude ... Correction; six-fifty miles. Correction; six hundred.” He paused. “Traffic is decelerating rapidly. I think, sir, this is the reported ship.”

And then there was a barely audible whining noise high in the air to the west. It grew in volume and changed in pitch. From a whine it became a scream. From a scream it rose to a shriek. Something monstrous and red glittered in the dying sunlight. It was huge. It was of no design ever known on earth. Wings supported it, but they were obscured by the blasts of forward rockets checking its speed.

It was dropping rapidly. Then lifting-rockets spouted flame to keep it from too rapid a descent. It cleared a mountain-peak by a bare two hundred feet, some two miles to the south. It was a hundred-odd feet in length. It was ungainly in shape, monstrous in conformation.

Colossal rocket-tubes behind it now barely trickled vaporous discharges. It cleared the mountain-top, went heavily on in a steep glide downward, and vanished behind a mountain-flank. Presently the thin mountain air brought the echoed sound of its landing, of rapid-fire explosions of rocket-tubes, and then silence.

Thorn Hard was snapping swift, staccato sentences into the report-transmitter. Describing the clumsy glittering monster, its motion; its wings; its method of propulsion. It seemed somehow familiar despite its strangeness. He said so.

Then a vivid blue flame licked all about the rim of the world and was gone. Simultaneously the G.C. speaker crashed explosively and went dead. Thorn went on grimly, switching in the spare.

“A very violent electrical discharge went out from it then. A blue light seemed to flash all around the horizon at no great distance and my speaker blew out. I have turned on the spare. I do not know whether my sender is functioning--”

The spare speaker cut in abruptly at that moment:

“It is. Stay where you are and observe. A squadron is coming.”

Then the voice broke off, because a new sound was coming from the speaker. It was a voice that was unhuman and queerly horrible and somehow machine-like. Hoots and howls and whistles came from the speaker. Wailing sounds. Ghostly noises, devoid of consonants but broadcast on a wave-length close to the G.C. band and therefore produced by intelligence, though unintelligible. The unhuman hoots and wails and whistles came through for nearly a minute, and stopped.

“Stay on duty!” snapped the G.C. speaker. “That’s no language known on earth. Those are Martians!”

Thorn looked up to see Sylva standing by the Watch-plane door. Her face was pale in the growing darkness outside.

“Beginning duty sir,” said Thorn steadily, “I report that I have with me Miss Sylva West, my fiancée, in violation of regulations. I ask that her family be notified.”

He snapped off the lights and went with her. The red rocket-ship had landed in the very next valley. There was a glare there, which wavered and flickered and died away.

“Martians!” said Thorn in fine irony. “We’ll see when the Watch planes come! My guess is Com-Pubs, using a searchlight! Nervy!”

The glare vanished. There was only silence, a curiously complete and deadly silence. And Thorn said, suddenly:

“There’s no wind!”

There was not. Not a breath of air. The mountains were uncannily quiet. The air was impossibly still, for a mountain-top. Ten minutes went by. Twenty. The detector-whistles shrilled.

“There’s the Watch,” said Thorn in satisfaction. “Now we’ll see!”

And then, abruptly, there was a lurid flash in the sky to northward.

Two thousand feet up and a mile away, the unearthly green blaze of a hexynitrate explosion lit the whole earth with unbearable brilliance.

“Stop your ears!” snapped Thorn.

The racking concussion-wave of hexynitrate will break human eardrums at an incredible distance. But no sound came, though the seconds went by ... Then, two miles away, there was a second gigantic flash...

Then a third ... But there was no sound at all. The quiet of the hills remained unbroken, though Thorn knew that such cataclysmic detonations should be audible at twenty miles or more. Then lights flashed on above. Two--three--six of them. They wavered all about, darting here and there ... Then one of the flying searchlights vanished utterly in a fourth terrific flash of green.

“The watch planes are going up!” said Thorn dazedly. “Blowing up! And we can’t hear the explosions!”

Behind him the G.C. speaker barked his call. He raced to get its message.

“The Watch planes we sent to join you,” said a curt voice he recognized as that of the Commanding General of the United Nations,

“have located an invisible barrier by their sonic altimeters. Four of them seem to have rammed it and exploded without destroying it. What have you to report?”

“I’ve seen the flashes, sir,” said Thorn unsteadily, “but they made no noise. And there’s no wind, sir. Not a breath since the blue flash I reported.”

A pause.

“Your statement bears out their report,” said the G.C. speaker harshly. “The barrier seems to be hemispherical. No such barrier is known on Earth. These must be Martians, as the Com-Pubs said. You will wait until morning and try to make peaceful contact with them. This barrier may be merely a precaution on their part. You will try to convince them that we wish to be friendly.”

“I don’t believe they’re Martians, sir--”

Sylva came racing to the door of the plane.

“Thorn! Something’s coming! I hear it droning!”

Thorn himself heard a dull droning noise in the air, coming toward him.

“Occupants of the rocket-ship, sir,” he said grimly, “seem to be approaching. Orders?”

“Evacuate the ship,” snapped the G.C. phone. “Let them examine it.

They will understand how we communicate and prepare to receive and exchange messages. If they seem friendly, make contact at once.”

Thorn made swift certain movements and dived for the door. He seized Sylva and fled for the darkness below the plane. He was taking a desperate risk of falling down the mountain-slopes. The droning drew near. It passed directly overhead. Then there was a flash and a deafening report. A beam of light appeared aloft. It searched for and found Thorn’s plane, now a wreck. Flash after flash and explosion after explosion followed...

They stopped. Their echoes rolled and reverberated among the hills.

There was a hollow, tremendous intensification of the echoes aloft as if a dome of some solid substance had reflected back the sound. Slowly the rollings died away. Then a voice boomed through a speaker overhead, and despite his suspicions Thorn felt a queer surprise. It was a human voice, a man’s voice, full of a horrible amusement.

“Thorn Hardt! Thorn Hardt! Where are you?” Thorn did not move or reply. “If I haff not killed you, you hear me,” the voice chuckled.

“Come to see me, Thorn Hardt. Der dome of force iss big, yes, but you can no more get out than your friends can get in. And now I haff destroyed your phones so you can no longer chat with them. Come and see me, Thorn Hardt, so I will not be bored. We will discuss der Com-Pubs. And bring der lady friend. You may play der chaperon!”

The voice laughed. It was not pleasant laughter. And the humming drone in the air rose and dwindled. It moved away from the mountain-top. It lessened and lessened until it was inaudible. Then there was dead silence again.

“By his accent, he’s a Baltic Russian,” said Thorn very grimly in the darkness. “Which means Com-Pubs, not Martians, though we’re the only people who realize it; and they’re starting a war! And we, Sylva, must warn our people. How are we going to do it?”

She pressed his hand confidently, but it did not look promising. Thorn Hard was on foot, without a transmitter, armed only with his belt-weapons and with a girl to look after, and moreover imprisoned in a colossal dome of force which hexynitrate had failed to crack...

It was August 20, 2037. There was a triple murder in Paris which was rumored to be the work of a Com-Pub spy, though the murderer’s unquestionably Gallic touches made the rumor dubious. Newspaper vendor-units were screaming raucously, “Martians land in Colorado!” and the newspapers themselves printed colored-photos of hastily improvised models in their accounts of the landing of a blood-red rocket-ship in the widest part of the Rockies. The inter-continental tennis matches reached their semi-finals in Havana, Cuba. Thorn Hard had not reported to Watch headquarters in twelve hours. Quadruplets were born in Des Moines, Iowa. Krassin, Commissar of Commissars of the Com-Pubs, made a diplomatic inquiry about the rumors that a Martian space-ship had landed in North America. He asked that Com-Pub scientists be permitted to join in the questioning and examination of the Martian visitors. The most famous European screen actress landed from the morning Trans-Atlantic plane with her hair dyed a light lavender, and beauty-shops throughout the country placed rush orders for dye to take care of the demand for lavender hair which would begin by mid-afternoon. The heavy-weight champion of the United Nations was warned that his title would be forfeited if he further dodged a fight with his most promising contender. And ... Thorn Hard had not reported to Watch headquarters in twelve hours.

He was, as a matter of fact, cautiously parting some bushes to peer past a mountain-flank at the red rocket-ship. Sylva West lay on the ground behind him. Both of them weary to the point of exhaustion. They had started their descent from Mount Wendel at the first gray streak of dawn in the east. They had toiled painfully across the broken country between, to this point of vantage. Now Thorn looked down upon the rocket-ship.

It lay a little askew upon the ground, seeming to be partly buried in the earth. A hundred feet and more in length, it was even more obviously a monstrosity as he looked at it in the bright light of day.

But now it was not alone. Beside it a white tower reared upward. Pure white and glistening in the sunshine, a bulging, uneven shaft rose a hundred feet sheer. It looked as solid as marble. Its purpose was unguessable. There was a huge, fan-shaped space where the vegetation about the rocket-ship was colored a vivid red. In air-photos, the rocket-ship would look remarkably like something from another planet.

But nearby, Thorn could see a lazy trickle of fuel-fumes from a port-pipe on one side of the monster...

“That tower is nothing but cellate foam, which hardens. And Sylva!

See?”

She came cautiously through the brushwood and looked down. She shivered a little. From here they could see beneath the bows of the rocket-ship. And there was a name there, in the Cyrillic alphabet which was the official written language of the Com-Pubs. Here, on United Nations soil, it was insolent. It boasted that the red ship came, not from an alien planet, but from a nation more alien still to all the United Nations stood for. The Com-Pubs--the Union of Communist Republics--were neither communistic nor republics, but they were much more dangerous to the United Nations than any mere Martians would have been.

“We’ll have some heavy ships here to investigate, soon,” said Thorn grimly. “Then I’ll signal!”

He flung back his head. High up and far away, beyond that invisible barrier against which Watch-planes had flung themselves in vain, there were tiny motes in mid-air. These were Watch planes too, hovering outside the obstacle they could not see, but which even hexynitrate bombs could not break through. And very far away indeed there was a swiftly-moving small dark cloud. As Thorn watched, that cloud drew close. As his eyes glowed, it resolved itself into its component specks. Small, two-man patrol-scouts. Larger, ten-man cruisers of the air. Huge, massive dreadnaughts of the blue. A complete combat-squadron of the United Nations Fighting Forces was sweeping to position about the dome of force above the rocket-ship.

The scouts swept forward in a tiny, whirling cloud. They sheered away from something invisible. One of them dropped a smoking object. It emitted a vast cloud of paper, which the wind caught and swept away, and suddenly wrapped about a definite section of an arc. More and more of the tiny smoke-bombs released their masses of cloudlike stuff. In mid-air a dome began to take form, outlined by the trailing streaks of gray. It began to be more definitely traced by interlinings. An aerial lattice spread about a portion of a six-mile hemisphere. The top was fifteen thousand feet above the rocket-ship, twenty-five thousand feet from sea-level, as high as Mount Everest itself.

Tiny motes hovered even there, where the smallest of visible specks was a ten-man cruiser. And one of the biggest of the aircraft came gingerly up to the very inner edge of the lattice-work of fog and hung motionless, holding itself aloft by powerful helicopter screws. Men were working from a trailing stage--scientists examining the barrier even hexynitrate would not break down.

Thorn set to work. He had come toilsomely to the neighborhood of the rocket-ship because he would have to do visual signaling, and there was no time to lose. The dome of force was transparent. The air fleet would be trying to communicate through it with the Martians they believed were in the rocket-ship. Sunlight reflected from a polished canteen would attract attention instantly from a spot near the red monster, while elsewhere it might not be observed for a long time.

But, trying every radio wave-band, and every system of visual signaling, and watching and testing for a reply, Thorn’s signal ought to be picked up instantly.

He handed his pocket speech-light receptor to Sylva. It is standard equipment for all flying personnel, so they may receive non-broadcast orders from flight leaders. He pointed to a ten-man cruiser from which shone the queer electric-blue glow of a speech-light.

“Listen in on that,” he commanded. “I’m going to call them. Tell me when they answer.”

He began to flash dots and dashes in that quaintly archaic telegraph alphabet Watch fliers are still required to learn. It was the Watch code call, sent over and over again.

“They’re trying to make the Martians understand,” said Sylva unsteadily with the speech-light receiver at her ear.

Flash--flash--flash ... Thorn kept on grimly. The canteen top was slightly convex, so the sunlight-beam would spread. Accuracy was not needed, therefore. He covered and uncovered it, and covered and uncovered it...

“They answered!” said Sylva eagerly. “They said ‘Thorn Hard report at once!’”

There was a hissing, roaring noise over the hillside, where the red rocket-ship lay. Thorn paid no attention. He began to spell out, in grim satisfaction:

“R-o-c-k-e-t s-h-i-p i-s--”

“Look out!” gasped Sylva. “They say look out, Thorn!”

Then she screamed. As Thorn swung his head around, he saw a dense mass of white vapor rushing over the hillside toward them. He picked Sylva up in his arms and ran madly...

The white vapor tugged at his knees. It was a variation of a vortex-stream. He fought his way savagely toward higher ground. The white vapor reached his waist ... It reached his shoulders ... He slung Sylva upon his shoulder and fought more madly still to get out of the wide white current ... It submerged him in its stinging, bitter flood ... As he felt himself collapsing his last conscious thought was the bitter realization that the bulbous white tower had upheld television lenses at its top, which had watched his approach and inspection of the rocket-ship, and had enabled those in the red monster to accurately direct their spurt of gas.

His next sensation was that of pain in his lungs. Something that smarted intolerably was being forced into his nostrils, and he battled against the agony it produced. And then he heard someone chuckle amusedly and felt the curious furry sensation of electric anesthesia beginning...

When he came to himself again a machine was clicking erratically and there was the soft whine of machinery going somewhere. He opened his eyes and saw red all about him. He stirred, and he was free.

Painfully, he sat up and blinked about him with streaming, gas-irritated eyes. He had been lying on a couch. He was in a room perhaps fifteen feet by twenty, of which the floor was slightly off-level. And everything in the room was red. Floor and walls and ceiling, the couch he had lain on and the furniture itself. There was a monstrous bulk of a man sitting comfortably in a chair on the other side of the room, pecking at a device resembling a writing-machine.

Thorn sat still for an instant, gaining strength. Then he flung himself desperately across the room, his fingers curved into talons.

Five feet, ten, with the slant of the floor giving him added impetus ... Then his muscles tightened convulsively. A wave of pure agony went through his body. He dropped and lay writhing on the floor, while the high-frequency currents of an induction-screen had their way with him. He was doubled into a knot by his muscles responding to the electric stimulus instead of his will. Sheer anguish twisted him. And the room filled with a hearty bellow of laughter. The monstrous whiskered man had turned about and was shaking with merriment.

He picked up a pocket-gun from beside him and turned off a switch at his elbow. Thorn’s muscles were freed.

“Go back, my friendt,” boomed the same voice that had come from a speaker the night before. “Go to der couch. You amuse me and you haff already been useful, but I shall haff no hesitation in killing you.

You are Thorn Hardt. My name is Kreynborg. How do you do?”

“Where’s my friend?” demanded Thorn savagely. “Where is she?”

“Der lady friendt? There!” The whiskered man pointed negligently with the pocket-gun. “I gafe her a bunk to slumber in.”

There was a niche in the wall, which Thorn had not seen. Sylva was there, sleeping the same heavy, dreamless sleep from which Thorn himself had just awakened. He went to her swiftly. She was breathing naturally, though tears from the irritating gas still streaked her face and her skin seemed to be pinkened a little from the same cause.

Thorn swung around. His weapons were gone, of course. The huge man snapped on the induction-screen switch again and put down his weapon.

With that screen separating the room into two halves, no living thing could cross it without either such muscular paralysis as Thorn had just experienced, or death. Coils in the floor induced alternating currents in the flesh itself, very like those currents used for supposed medical effects in “medical batteries,” and “shockers.”

“Be calm!” said Kreynborg, chuckling. “I am pleased to haff company.

This is der loneliest spot in der Rockies. It was chosen for that reason. But I shall be here for maybe months, and now I shall not be lonely. We of der Com-Pubs haff scientific resources such as your fools haff nefer dreamed of, but there is no scientific substitute for a pretty woman.”

He turned again to the writing device. It clicked half a dozen times more, and he stopped. A strip of paper came out of it. He inserted it into the slot of another mechanism and switched on a standard G.C. phone as the paper began to feed. In seconds the room was filled with unearthly hoots and wails and whistles. They came from the device into which the paper was feeding, and they poured into the G.C. transmitter. They went on for nearly a minute, and ceased. Kreynborg shut off the transmitter.

“My code,” he observed comfortably, “gifing der good news to Stalingrad. Everything is going along beautifully. I roused der fair Sylva and kissed her a few times to make her scream into a record, and I interpolated her screamings into der last code transmission. Your wise men think der Martians haff vivisected her. They are concentrating der entire fighting force of der United Nations outside der dome of force. And all for a few kisses!”

Thorn was white with rage. His eyes burned with a terrible fury. His hands shook. Kreynborg chuckled again.

“Oh, she is unharmed--so far. I haff not much time now. Presently der two of you will while away der time. But not now.”

He switched on the G.C. receiver and the room filled with a multitude of messages. Thorn sat beside Sylva, watching, watching, watching, while invisible machinery whined softly and Kreynborg listened intently to the crisp, curt official reports that came through on the Fighting Force band. Three combat-squadrons were on the spot now; One, Three and Eight. Four more were coming at fast cruising speed--four hundred miles an hour. One combat-squadron of the whole fleet alone would be left to cope with all other emergencies that might arise ... A television screen lighted up and Thorn could see where the lenses on the bulbous tower showed the air all about filled with fighting-planes, hovering about the dome of force like moths beating their wings against a screen. The strongest fighting-force in the world, helpless against a field of electric energy!

“It is amusing,” chuckled Kreynborg, looking at the screen complacently. “Der dome of force is a new infention. It is a heterodyning of one frequency upon another at a predetermined distance. It has all der properties of matter except mass and a limit of strength. There is no limit to its strength! But it cannot be made except in a sphere, so at first it seemed only a defensif weapon. With it, we could defy der United Nations to attack us. But we wished to do more. So I proposed a plan, and I haff der honor of carrying it out.

If I fail, Krassin disavows me. But I shall not fail, and I shall end as Commissar for der continent of North America!”

He looked wisely at Thorn, who sat motionless.

“You keep quiet, eh, and wait for me to say something indiscreet?

Ferry well, I tell you. We are in a sort of gold-fish globe of electric force. Your air fleet cannot break in. You know that! Also, if they were in they could not break out again. So I wait, fery patiently pretending to be a Martian until all your Fighting Force has gathered around in readiness to fight me. But I shall not fight. I shall simply make a new and larger gold-fish globe, outside of this one. And then I go out and make faces at der Fighting Force of der United Nations imprisoned between der two of them--and then der Com-Pub fleet comes ofer!”

He stood up and put his hand on a door-knob.

“Is it not pretty?” he asked blandly. “In two weeks der air fleet will begin to starfe. In three, there will be cannibalism, unless der Com-Pubs accept der surrender. Imagine...” He laughed. “But do not fear, my friendt! I haff profisions for a year. If you are amusing, I feed you. In any case I exchange food for kisses with der charming Sylva. It will be amusing to change her from a woman who screams as I kiss her, to one who weeps for joy. If I do not haff to kill you, you shall witness it!”

He vanished through a doorway on the farther side of the room.

Instantly Thorn was on his feet. The dead slumber in which Sylva was sunk was wholly familiar. Electric anesthesia, used not only for surgery, but to enforce complete rest at any chosen moment. He dragged her from that couch to his own. He saw her stir, and her eyes were instantly wide with terror. But Thorn was tearing the couch to pieces.

Cover, pneumatic mattress ... He ripped out a loosely-fitting frame-piece of steel.

“Quick, now,” he said in a low tone, “I’m going to short the induction-screen. We’ll get across it. Then--out the door!”

She struggled to her feet, terrified, but instantly game. Thorn slid the rod of metal across the stretch of flooring he had previously been unable to cross. The induced currents in the rod amounted to a short-circuit of the field. The rod grew hot and its paint blistered smokily. Thorn leaped across with Sylva in his wake. He pointed to the door, and she fled through it. He seized a chair, crashed it frenziedly into the television screen, and had switched on the G.C. phone when there was a roar of fury from Kreynborg. Instantly there was the spitting sound of a pocket-gun and in the red room the racking crash of a hexynitrate pellet. Nothing can stand the instant crash of hexynitrate. Its concussion-wave is a single pulsation of the air. The cellate diaphragm of the G.C. transmitter tore across from its violence and Thorn cursed bitterly. There was no way, now, of signaling...

A second racking crash as a second pellet flashed its tiny green flame. Kreynborg was using a pocket-gun, one of those small terrible weapons which shoot a projectile barely larger than the graphite of a lead pencil, but loaded with a fraction of a milligram of hexynitrate.

Two hundred charges would feed automatically into the bore as the trigger was pressed.

Thorn gazed desperately about for weapons. There was nothing in sight.

To gain the outside world he had to pass before the doorway through which the bullets had come ... And suddenly Thorn seized the code-writer and the device which transmitted that code as a series of unearthly noises which the world was taking for Martian speech. He swung the two machines before the door in a temporary barrier.

Whatever else Kreynborg might be willing to destroy, he would not shoot into them!

Thorn leaped madly past the door as Kreynborg roared with rage again.

He paused only to hurl a chair at the two essential machines, and as they dented and toppled, he fled through the door and away.