But already he was stepping silently backward, concealed in the abyss-black gloom of the chamber. He reached noiselessly behind him for the knob of the door. He was being a fool and he knew it. But he had seen honesty in her eyes, back on the skid, and even the yearning for revenge couldn't make him blot that out with pyro-flame. 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!" His voice was a bellow--there was no time for whispers. No time, and perhaps no need. If the dome had gone, Avalon might be a city of corpses, heat suits or none, before help could arrive with fresh oxygen tanks from far-away Aylette. Disguise would hardly matter then. But he wasted no time in thought. He was out the door, down the hall and dropping into the cushioning grav-web of the descending shaft in seconds. Guests were waking in their rooms. The corridors were filling with shouting men and women. The shriek of emergency trucks filtered in from the street, and the hoarse bellow of the alarm sirens multiplied the havoc done to the peace of the night. If he could get to a ship--? But the slidewalks would be jammed with panicky humans, all with the same thought. A heat suit was his only chance. And the nearest ones he knew of were at South Lock, at the base of the dome itself!