At once the air-car made towards it and slid into the tube leading through the hill. Quickly it was in the chamber of the lock, the outer door closed automatically behind, the water was drained out, and then the inner door opened and the car, dripping, emerged into the brilliantly-lit hangar and went to rest in its mooring cradle beside Leithgow's space-ship. A minute later its passengers were in the laboratory of the Master Scientist. * * * * * Dr. Ku Sui took in the arrangements made in the laboratory with a swift glance, and then his eyes went to a door that opened in the opposite wall and to the slight, smock-garbed figure that came through it. He smiled. "Ah, Master Leithgow! A return visit, you see. At Captain Carse's invitation. It is very interesting to me, this home of yours: so cleverly concealed!" Leithgow vouchsafed his archenemy no more than a look, but turned to the Hawk. "You are ready, Carse?" "Some preliminaries first, Eliot. These men, the four whites and the yellow, must be put in some place of safety. You can take care of them, Ban. One of the storerooms; lock them in. You remember your way? Then, better take off your suit." Ban nodded, and led the five robot humans out. Leithgow, Hawk Carse and Ku Sui were left alone in the laboratory, and for a minute there was silence. How much had passed between these three! How many plots, and counter-plots: how much blood: how many lives affected! The feud of Hawk Carse and Dr. Ku Sui--and Eliot Leithgow, who was the chief cause of it--here again had come to a head. Here again were all the varied forces of brains and guile, science and skill, marshaled in the great, vital game on whose outcome depended the restoration of Eliot Leithgow and the lives of the coordinated brains and, indeed, though more distantly, the fate of all the tribes of men on all the planets. For if Ku Sui won free he would go on irresistibly, and his goal was the domination of the solar system.... Three men, alone in a room--and the course of the creature Man being affected by their every move. Large words: but the histories of the period bear them out. Though, doubtless, Ku Sui alone knew how great were the stakes as they stood there in the laboratory. * * * * * Hawk Carse was uneasy. The odds seemed all on his side--yet there was Ku Sui's strange, almost imperceptible smile, his mysterious words up on the asteroid, his smooth, unruffled assurance! What did these things mean? He intended now to find out. He said, tersely: