"Mallory," Greg went on, "I have what you've always needed--means of generating almost unlimited energy at almost no cost, the secret of the energy of matter. A secret that will smash Interplanetary, that will free the Solar System from Spencer Chambers. But I can't make that secret available to the people until Chambers is crushed, until I'm sure that he can't take it from me. And to do that I need your help." Mallory's face lost its expression of bewilderment, suddenly lighted with realization. But his voice was harsh and bitter. "You came too late. I can't help you. Remember, I'm in a prison ship from which no one can escape. You have to do what you can ... you must do what you can. But I can't be with you." Manning strode forward. "You don't get the idea at all. I said I'd get you out of here and I'm going to. I could pick up this ship and put it wherever I wanted. But I don't want to. I just want you." Mallory stared at him. "Just don't be startled," said Greg. "Something will happen soon. Get ready for it." Feet drummed on the metal corridor outside. "Hey, you, pipe down!" yelled the voice of the guard. "You know there's no talking allowed now. Go to sleep." "That's the guard," Mallory whispered fiercely. "They'll stop us." Greg grinned viciously. "No, they won't." * * * * * The guard came into view through the grilled door. "So it's you, Mallory ..." he began, stopping in amazement. "Hey, you!" he shouted at Greg. "Who are you? How did you get in that cell?" Greg flipped a hand in greeting. "Pleasant evening, isn't it?" The guard grabbed for the door, but he did not reach the bars. Some force stopped him six inches away. It could not be seen, could not be felt, but his straining against it accomplished nothing. "Mallory and I are leaving," Greg told the guard. "We don't like it here. Too stuffy." The guard lifted a whistle and blew a blast. Feet pounded outside. A prisoner yelled from one of the cells. Another catcalled. Instantly the ship was in an uproar. The convicts took up the yammering, shaking the bars on their doors. "Let's get started," Greg said to Mallory. "Hold tight." Blackness engulfed Mallory. He felt a peculiar twisting wrench. And then he was standing in the control room of a ship and Gregory Manning and another man were smiling at him. White light poured down from a cluster of globes. Somewhere in the ship engines purred with the hum of power. The air was fresh and pure, making him realize how foul and stale the air of the prison ship had been. Greg held out his hand. "Welcome to our ship." Mallory gripped his hand, blinking in the light. "Where am I?" "You are on the _Invincible_, five million miles off Callisto." "But were you here all the time?" asked Mallory. "Were you in my cell back there or weren't you?"