"I don't know myself, Mark. These weeks, I've been a prisoner here—a prisoner talking on a voco. They've never let me come or go." On once more. On about the walls, and on, turn after turn. On, while mankind's life-span ticked away. The door came under my groping fingers. I clutched the knob; shook it. It didn't give. Something snapped inside me. Wildly, I flung myself at the heavy portal—kicking it, clawing it, beating on it with my fists. No answer. I yelled—a fierce, shrill cry to wake the dead. Again, again, again ... hammering and screaming, screaming and hammering. Celeste: "Mark, stop it, stop it! stop it! They won't come. You'll only hurt yourself!" Panting, I drew back, crouched, and then lunged for the slab that blocked our way, hurling myself against it with all my weight and strength. "Mark, Mark—!" Again I lunged. Again—again—again.... My shoulders were bruised now, my whole body aching. It was all I could do to stumble back for still another try. Only then, suddenly, light spilled in upon us as the door swung open. Unbelieving, I rocked back. Celeste Stelpa gave a choked, incoherent cry. Wider the door swung, and still wider. I held my breath and tensed my belly, waiting to see what form our foe would take. Nothing happened. I looked round at Celeste, and she at me. Still nothing.