"At any rate," Lee said, "I'm convinced that there was a human culture a million years ago; that it expanded out through the Solar System and to the stars; that it met an implacably hostile alien race; and that the humans were utterly defeated. Nearly wiped out." "And the machine out there?" "It was built by the Others. It's alien. And hostile," Lee said. "That's why we must find out what it's doing, and how." * * * * * You could feel the change in attitude throughout the center after that conference. An invisible, but almost palpable wave of tension swept through every office, every lab, every section of the underground community. Not everyone believed Lee's theory about the Others. But they could never look at those strange buildings again without wondering. What had been a puzzling, frustrating riddle took on the attributes of a living, intelligent enemy; an enemy that mocked their efforts to understand, to control; an enemy that seemed in every way superior to the feeble powers of the men from Earth. * * * * * A few days after that conference, Dr. Bennett left Titan for good. Lee was in full command now. He was just finishing a quick lunch at the robocafeteria when Elaine walked by and stopped at his table. "Hi boss. I'm on my way out to the buildings. Want to come along?" Lee punched a button at the end of the table, and the dishes slid into a wall receptacle. "No thanks," he said. "I've got some paperwork to do...." "Sid, you're going to have to come out and face it sooner or later. Why don't you come now? There's practically nobody there." He looked up at her. "You're not a part-time psychotech, are you?" "No," she said, grinning. "But I wouldn't want anybody to start thinking that you're afraid to go into the buildings. And I especially don't want _you_ to think that." "Okay," he said, getting up from his chair. "You're right ... as usual." They took a lift chute to the surface bubble, a dome of clear plastisteel that housed ground vehicles and miscellaneous outdoor equipment. There they squirmed into pressure suits, complete with fishbowl helmets. After checking out their oxygen tanks, heaters and radios, they were ready to go outside. "Want to walk?" Elaine asked. Lee nodded. It took him a few minutes to get accustomed to the low-gravity shuffle that you must employ to walk on Titan, with its one-third Earth gravity. They headed for the buildings, under the double shadows cast by the distant Sun and the ever-present, overpowering Saturn. The buildings loomed straight up from the dark plain, gaunt gloomy specters from a bygone age haunting this shadow world. There were five low, square featureless structures ringed around a central pentagonally-shaped tower that swept upward to a series of spires and antennas. Several doors had been cut into the outer buildings' walls by the inquiring Earthmen. Originally, the walls had been perfectly blank.