It was at about this time that the siren in the Shed began its choppy, hiccoughing series of warm-up notes. The news from Canada arrived, as a matter of fact, some thirty seconds after the outer-perimeter radar screen around the Platform gave its warning. Then there was no hesitation or delay at all. Men were already tumbling out of bed at three airfields, buckling helmets and hoping their oxygen tanks would function properly. Then the radars atop the Shed itself picked up the moving speck. And small blue-white flames began to rise from the ground and go streaking away in the darkness in astonishing numbers.

The covers of the guns at the top of the Shed slid aside. Miles away, jet planes shot skyward, and newly wakened pilots looked at their night-fighting instruments and swore unbelievingly at the speed they were told the plunging object was making. The jet pilots gave their motors everything they could take, but it didn’t look good.

The planes of the jet umbrella over the Shed stopped cruising and sprinted. And they were the only ones likely to get in front of the object in time.

Inside the Shed, the siren howled dismally and all the Security men were snapping: “Radar alarm! All out! Radar alarm! All out!”

And men were moving fast, too. Some came down from the Platform on hoists, dropping with reckless speed to the floor level. Some didn’t wait for a turn at that. They slid down one upright, swung around the crosspiece on the level below, and slid down another vertical pipe. For a minute or more it looked as if the scaffolds oozed black droplets which slid down its pipes. But the drops were men. The floor became speckled and spotted with dots running for its exits.

The siren ceased its wailing and its noise went down and down in pitch until it was a baritone moan that dropped to bass and ceased. Then there was no sound but the men moving to get out of the Shed. There were trucks, too. Those that had been loading with dismantled scaffolding roared for the doors to get out and away. Some men jumped on board as they passed. The exit doors swung up to let them go.

But it was very quiet in the Shed, at that. There was no noise but a few fleeing trucks, and the murmur which was the voices of the Security men hurrying the work crew out. There was less to hear than went on ordinarily. And it was a long distance across the floor of the Shed.

Joe stood with his fists clenched absurdly. This could only be an air attack. An air attack could only mean an atom-bomb attack. And if there was an atom bomb dropped on the Shed, there’d be no use getting outside. It wouldn’t be merely a fission bomb. It would be a hell bomb—a bomb which used the kind of bomb that shattered Hiroshima only as a primer for the real explosive. Nobody could hope to get beyond the radius of its destruction before it hit!

Joe heard himself raging. He’d thought of Sally. She’d be in the range of annihilation, too. And Joe knew such fury and hatred—because of Sally—that he forgot everything else.

He didn’t run. He couldn’t escape. He couldn’t fight back. But because he hated, he had to do something to defy.