For alternating fifteen-second periods the sunlight filled the dome and its buildings; and on the tail of the first of these, even as the sable tide swept all vision from him, the Hawk arrived at the door of one wing of the central building. He had not seen Ku Sui, and he had no time for exploration, but he did have a hunch as to where the Eurasian had gone, and he followed that hunch. A silent, giant-gray thing in the black silence of the corridor, grim, intent and seeming irresistible, he swept along it; and every second he knew that a raygun might spit from where it had been waiting in ambush to puncture his suit and kill him. For whether or not Ku Sui was aware that he was being tracked by his old, bitter foe, Carse did not know. The asteroid plunged down faster and faster. Earth's atmosphere, with all its perils of friction, coming ever closer, and the great bosom of the planet lying waiting to receive and bury the rock hurtling towards it. Throughout most of the leagues of space that asteroid had tracked on its master's diverse errands, and in many distant places the trails of Hawk Carse and Ku Sui had crossed and left blood and crossed again; and now those three--asteroid, Eurasian and the Hawk--were drawn once more together for the spectacular and epic climax, now only minutes away. No power in the universe was to stop the plunge of the asteroid; it remained to be seen how one or both of the two living humans on it could get out in time.... But of all this, nothing was in Hawk Carse's mind except the beating, driving realization that few minutes were left in which to play out the last scene. With reckless haste he sped to where his hunch led him, the secret panel in Dr. Ku's laboratory. As he reached it, faint sunlight came filtering in from somewhere and he saw that the panel was open. He looked within and dimly saw a ladder reaching down into black depths. Without hesitation he thrust through the opening and dropped into the blackness. He dared not lose a second. * * * * * He hit bottom with a thud, changed his glove controls and reached out in the darkness. He felt that he was in one end of a passageway. As rapidly as he could, his arms stretched wide, all his nerves and muscles and senses alert, he pressed along it.