Pilot and co-pilot looked at each other. "Tell him," said the pilot. "About five months ago," said the co-pilot, "there was an Army colonel wangled a ride to Bootstrap on a cargo plane. The plane took off. It flew all right until twenty miles from Bootstrap. Then it stopped checking. It dove straight for the Shed the Platform's being built in. It was shot down. When it hit, there was an explosion." The co-pilot shrugged. "You won't believe me, maybe. But a week later they found the colonel's body back east. Somebody'd murdered him." Joe blinked. "It wasn't the colonel who rode as a passenger," said the co-pilot. "It was somebody else. Twenty miles from Bootstrap he'd shot the pilots and taken the controls. That's what they figure, anyhow. He meant to dive into the construction Shed. Because--very, very cleverly--they'd managed to 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."