Duane stared at him a long second, then nodded abruptly. "I was right the first time," he said. "I'll _have_ to kill you!" * * * * * Already his hand was streaking toward the grip of his dis-gun, touching it, drawing it forth. But the white-haired man was faster. His arms swept up and pinioned Duane, holding him impotent. "Don't be a fool," he grated. "Duane--" The P.A. speaker rattled, blared something unintelligible. Neither man heard it. Duane lunged forward into the taller man's grip, sliding down to the floor. The white-haired man grappled furiously to keep his hold on Peter's gun arm, but Peter was slipping away. Belatedly, Stevens went for his own gun. He was too late. Duane's was out and leveled at him. "_Now_ will you listen to reason?" Duane panted. But he halted, and the muzzle of his weapon wavered. The floor swooped and surged beneath him as the thrust of the mighty jets was cut off. Suddenly there was no gravity. The two men, locked together, floated weightlessly out to the center of the corridor. "Course change!" gasped white-haired Stevens. "Good God!" The ship had reached the midpoint of its flight. The bells had sounded, warning every soul on it to take shelter, to strap themselves in their pressure bunks against the deadly stress of acceleration as the ship reversed itself and began to slow its headlong plunge into Callisto. But the two men had not heeded. The small steering rockets flashed briefly. The men were thrust bruisingly against the side of the corridor as the rocket spun lazily on its axis. The side jets flared once more to halt the spin, when the one-eighty turn was completed, and the men were battered against the opposite wall, still weightless, still clinging to each other, still struggling. Then the main-drive bellowed into life again, and the ship began to battle against its own built-up acceleration. The corridor floor rose up with blinking speed to smite them-- And the lights went out in a burst of crashing pain for Peter Duane. * * * * * Someone was talking to him. Duane tried to force an eye open to see who it was, and failed. Something damp and clinging was all about his face, obscuring his vision. But the voice filtered in. "Open your mouth," it said. "Please, Peter, open your mouth. You're all right. Just swallow this." It was a girl's voice. Duane was suddenly conscious that a girl's light hand was on his shoulder. He shook his head feebly. The voice became more insistent. "Swallow this," it said. "It's only a stimulant, to help you throw off the shock of your--accident. You're all right, otherwise." Obediently he opened his mouth, and choked on a warm, tingly liquid. He managed to swallow it, and lay quiet as deft feminine hands did something to his face. Suddenly light filtered through his closed eyelids, and cool air stirred against his damp face.