He opened the door, slid out, closed it softly behind him. The girl said nothing, perhaps had not known he had gone. Nolan cast a quick longing glance at the other door, but there was no time. In seconds the girl would discover she was alone. There would be an alarm, surely.

A dim thread of light showed him the door to the hall. Catlike he crossed to it, then halted, petrified. Men were coming down the hall, several of them by the voices. He caught a snatch of a rasping complaint: "Old man Woller's tin soldiers, that's us. Who the hell does he—"

Nolan swore lividly under his breath. The end of the trail had come.

But he stepped back a pace and stood there, pyro up-tilted and ready. He would have a split-second's advantage. If only there were no more than two or three of them—


And then the sound was drowned out. A sharp, moaning screech came from outside. A harsh metallic wail that climbed for the frigid heavens above, louder than the screaming trumpets of Ragnarök.

The alarm sirens! There was a break in the crystal dome that held the life of Avalon!

Meteorite, accident or simple fatigue—the dome had cracked. Air and heat would vanish. Death would tenant the city.

There was a sudden, sharp babble from the men outside, then the pounding of footsteps, halting as they dove into the grav-shaft. Nolan's chance! But he froze in his tracks, then whirled. He ran to the door behind him and wrenched it open.

"Get a heat suit!" he bawled to the girl on the bed. "Dome's cracked! You've got maybe twenty minutes—less, if it's a bad break!"