Kraag pointed the projectile pistol and pulled the trigger. Nothing happened. Then he realized that he had never released the pressure of his hand-hook on the trigger after firing the first time. He let up on it and pressed it down. And again Kraag was hurled backward, but this time he was smashed against the fuel tank and rebounded forward, falling on his face. By the time he reached his feet again, Jonner had vanished over the horizon. Cursing softly, Kraag made his way back to the personnel sphere. He had hoped to get Jonner with that shot. He was very sleepy, and now he was faced with another night on guard. He entered the airlock, pushed himself gently upward to catch the rungs of the metal ladder and turned the wheel of the airlock's inner door. Nothing happened. The door did not open. Fear gripped him like a paralyzing hand. For a moment he thought Jonner had managed to get to the sphere ahead of him and somehow had locked him out. But that was impossible. Then he thought the inner door might be jammed, and he and Jonner locked out together. He glanced frantically below him, then broke into relieved laughter. He had left the outer airlock door open. As a safety measure against the sphere's accidentally losing its air, neither door would open unless the other was shut. And that meant he could lock Jonner out of the sphere simply by leaving the inner door of the airlock open! His laugh was full and genuine now as he pulled the outer door closed. "Having fun, Kraag?" asked Jonner in his earphones. "Just looking forward to a good night's sleep, for a change," retorted Kraag triumphantly. "Prowl around all you want to, Jonner. I can wait you out, now." "The airlock, eh? I wondered when your guilty conscience would settle down and let you remember about that airlock," said Jonner phlegmatically. "You know, Kraag, I had no idea you wouldn't think about a simple thing like that, till I looked through the airlock port last night and saw you huddled up there with a heat-gun. You should have turned out the light." Jonner was silent for a few minutes. Then he added: "I don't think I'd laugh yet, though, Kraag. Remember, you're fighting with my weapons." Kraag wasn't sure what he meant by that: whether he was talking about Kraag's using the projectile pistol or the fact that they were in space, Jonner's natural element. Kraag himself had been in space 10 years, most of it with Jonner, but before then he had never left Earth. Jonner had been born and raised on Mars, where a man needed a suit to go to the next settlement, and he had been on a ship since he was 15. As for using the pistol, Kraag could see danger for no one but Jonner. He had proved, twice, that he could fire it. He was quite sure the old-fashioned weapon was no more likely to explode than a heat-gun. The only trouble he foresaw was figuring how to reload it if he used up all its projectiles before hitting Jonner.