get a bomb in the plane disguised as cargo. They got the men who’d done that, later, but it was rather late.”

Joe said dubiously: “But would one bomb destroy the Shed and the Platform?”

“This one would,” said the co-pilot. “It was an atom bomb. But it wasn’t a good one. It didn’t detonate properly. It was a fizz-off.”

Joe saw the implications. Cranks and crackpots couldn’t get hold of the materials for atom bombs. It took the resources of a large nation for that. But a nation that didn’t quite dare start an open war might try to sneak in one atom bomb to destroy the space station. Once the Platform was launched no other nation could dream of world domination. The United States wouldn’t go to war if the Platform was destroyed. But there could be a strictly local hot war.

The pilot said sharply: “Something down below!”

The co-pilot fairly leaped into his right-hand seat, his safety belt buckled in half a heartbeat.

“Check,” he said in a new tone. “Where?”

The pilot pointed.

“I saw something dark,” he said briefly, “where there was a deep dent in the cloud.”

The co-pilot threw a switch. Within seconds a new sound entered the cabin. Beep-beep-beep-beep. They were thin squeaks, spaced a full half-second apart, that rose to inaudibility in pitch in the fraction of a second they lasted. The co-pilot snatched a hand phone from the wall above his head and held it to his lips.

“Flight two-twenty calling,” he said crisply. “Something’s got a radar on us. We saw it. Get a fix on us and come a-running. We’re at eighteen thousand and”—here the floor of the cabin tilted markedly—“now we’re climbing. Get a fix on us and come a-running. Over!”

He took the phone from his lips and said conversationally: “Radar’s a giveaway. This is no fly-way. You wouldn’t think he’d take that much of a chance, would you?”

Joe clenched his hands. The pilot did things to the levers on the column between the two pilots’ seats. He said curtly: “Arm the jatos.”

The co-pilot did something mysterious and said: “Check.”

All this took place in seconds. The pilot said, “I see something!” and instantly there was swift, tense teamwork in action. A call by radio, asking for help. The plane headed up for greater clearance between it and the clouds. The jatos made ready for firing. They were the jet-assisted take-off rockets which on a short or rough field would double the motors’ thrust for a matter of seconds. In straightaway flight they should make the plane leap ahead like a scared rabbit. But they wouldn’t last long.

“I don’t like this,” said the co-pilot in a flat voice. “I don’t see what he could do——”

Then he stopped. Something zoomed out of a cloud. The action was completely improbable. The thing that appeared looked absolutely commonplace. It was a silver-winged private plane, the sort that cruises at one hundred and seventy-five knots and can hit nearly two-fifty if pushed. It was expensive, but not large. It came straight up out of the cloud layer and went lazily over on its back and dived down into the cloud layer again. It looked like somebody stunting for his own private lunatic pleasure—the kind of crazy thing some people do, and for which there is no possible explanation.

But there was an explanation for this.

At the very top of the loop, threads of white smoke appeared. They should have been unnoticeable against the cloud. But for the fraction of an instant they were silhouetted against the silver wings. And they were not misty wisps of vapor. They were dense, sharply defined rocket trails.

They shot upward, spreading out. They unreeled with incredible, ever-increasing velocity.

The pilot hit something with the heel of his hand. There was a heart-stopping delay. Then the transport leaped forward with a force to stop one’s breath. The jatos were firing furiously, and the ship jumped. There was a bellowing that drowned out the sound of the engines. Joe was slammed back on the rear wall of the cabin. He struggled against the force that pushed him tailward. He heard the pilot saying calmly: “That plane shot rockets at us. If they’re guided we’re sunk.”

Then the threads of smoke became the thickness of cables, of columns! They should have ringed the transport plane in. But the jatos had jumped it crazily forward and were still thrusting fiercely to make it go faster than any prop-plane could. The acceleration made the muscles at the front of Joe’s throat ache as he held his head upright against it.

“They’ll be proximity——”

Then the plane bucked. Very probably, at that moment, it was stretched far past the limit of strain for which even its factor of safety was designed. One rocket had let go. The others went with it. The rockets had had proximity fuses. If they had ringed the transport ship and gone off with it enclosed, it would now be a tumbling mass of wreckage. But the jatos had thrown the plane out ahead of the target area. Suddenly they cut off, and it seemed as if the ship had braked. But the pilot dived steeply, for speed.

The co-pilot was saying coldly into the microphone: “He shot rockets. Looked like Army issue three point fives with proximities. They missed. And we’re mighty lonely!”

The transport tore on, both pilots grimly watching the cloud bank below. They moved their bodies as they stared out the windows, so that by no possibility could any part of the plane mask something that they should see. As they searched, the co-pilot spoke evenly into the microphone at his lips: “He wouldn’t carry more than four rockets, and he’s dumping his racks and firing equipment now. But he might have a friend with him. Better get here quick if you want to catch him. He’ll be the innocentest private pilot you ever saw in no time!”

Then the pilot grunted. Something was streaking across the cloud formation far, far ahead. Three things. They were jet planes, and they seemed not so much to approach as to swell in size. They were coming at better than five hundred knots—ten miles a minute—and the transport was heading for them at its top speed of three hundred knots. The transport and the flight of jets neared each other at the rate of a mile in less than four seconds.

The co-pilot said crisply: “Silver Messner with red wing-tips. The number began——” He gave the letter and first digits of the vanished plane’s official designation, without which it could not take off from or be serviced at any flying field.

Joe heard an insistent, swift beep-beep-beep-beep which would be the radars of the approaching jets. He could not hear any answers that might reach the co-pilot as he talked to unseen persons who would relay his words to the jet fighters.

One of them peeled off and sank into the cloud layer. The others came on. They set up in great circles about the transport, crossing before it, above it, around it, which gave the effect of flying around an object not in motion at all.

The pilot flew on, frowning. The co-pilot said: “Yes. Sure! I’m listening!” There was a pause. Then he said: “Check. Thanks.”

He hung the instrument back where it belonged, above his head and behind him. He thoughtfully mopped his brow. He looked at Joe.

“Maybe,” he said mildly, “you believe me when I tell you there’s a sort of hot war on, to keep the Platform from taking off.”

The pilot grunted. “Here’s the third jet coming up.”

It was true. The jet that had dived into the clouds came up out of the cloud formation with somehow an air of impassive satisfaction.

“Did they spot the guy?”

“Yeah,” said the co-pilot.