Eleven levels later Rodney asked, "How much time have we now?" "Seven hours," Wass said quietly, "until take-off." "One more level," Martin said, ignoring the reference to time. "I ... think it's the last." They walked down the ramp and stood together, silent in a dim pool of artificial light on the bottom level of the alien city. Rodney played his torch about the metal figures carefully placed about the floor. "Martin, what if there are no reservoirs? What if there are cemeteries instead? Or cold storage units? Maybe the switch I pulled--" "Rodney! Stop it!" Rodney swallowed audibly. "This place scares me...." "The first time I was ever in a rocket, it scared me. I was thirteen." "This is different," Wass said. "Built-in traps--" "They had a war," Martin said. Wass agreed. "And the survivors retired here. Why?" Martin said, "They wanted to rebuild. Or maybe this was already built before the war as a retreat." He turned impatiently. "How should I know?" Wass turned, too, persistent. "But the planet was through with them." "In a minute," Martin said, too irritably, "we'll have a sentient planet." From the corner of his eye he saw Rodney start at that. "Knock it off, Wass. We're looking for reservoirs, you know." They moved slowly down the metal avenue, between the twisted shadow shapes, looking carefully about them. Rodney paused. "We might not recognize one." Martin urged him on. "You know what a man-hole cover looks like." He added dryly, "Use your imagination." They reached the metal wall at the end of the avenue and paused again, uncertain. Martin swung his flashlight, illuminating the distorted metal shapes. Wass said, "All this had a purpose, once...." "We'll disperse and search carefully," Martin said. "I wonder what the pattern was." "... The reservoirs, Wass. The pattern will still be here for later expeditions to study. So will we if we don't find a way to get out." Their radios recorded Rodney's gasp. Then--"Martin! Martin! I think I've found something!" Martin began to run. After a moment's hesitation, Wass swung in behind him. "Here," Rodney said, as they came up to him, out of breath. "Here. See? Right here." Three flashlights centered on a dark, metal disk raised a foot or more from the floor. "Well, they had hands." With his torch Wass indicated a small wheel of the same metal as everything else in the city, set beside the disk. From its design Martin assumed that the disk was meant to be grasped and turned. He wondered what precisely they were standing over. "Well, Skipper, are you going to do the honors?" Martin kneeled, grasped the wheel. It turned easily--almost too easily--rotating the disk as it turned. Suddenly, without a sound, the disk rose, like a hatch, on a concealed hinge. The three men, clad in their suits and helmets, grouped around the six-foot opening, shining their torches down into the thing that drifted and eddied directly beneath them.