Cautiously, Jonner poked the muzzle of his heat-gun around the edge of the control board. Methodically, he shot the three Marscorp men, one by one. They died without discovering the source of the invisible heat-beam that cut them down. Tyruss was dead. Cursing, Jonner went below, heat-gun in hand. On the centerdeck, Wessfeld's body floated. Wessfeld was dead, burned through the chest. Aron was not there. He found all three of the others, locked in the airlock, without spacesuits. Jonner watched Aron suspiciously as they emerged. "What happened?" he demanded of Aron. "I don't know," disclaimed Aron. "They woke us up. They had heat-guns then. Wessfeld tried to reach his, and they shot him. Stein and Farlan were already in the airlock when they brought me down." "Stein, were you and Farlan constantly in sight of each other, as ordered?" asked Jonner, watching Aron. Did Aron's eyes widen apprehensively? Stein started. "Why, no," he admitted. "Farlan was on the engine deck, and I was down in the airlock checking the spacesuits before blast-off. That's routine, you know. They herded Farlan down and caught me by surprise." "That's right," said Farlan. "I was checking the engines when they came through the hatch from above with heat-guns." "Damn!" exploded Jonner. "I gave everyone strict orders--all right, it's too late now. It just cost us two men, and one of the four of us left is a Marscorp spy. Everyone get above and strap down for acceleration." The spy was Aron or Farlan, but he still didn't know which. Aron could have feigned sleep, and slipped down to the storage deck to release and arm the Marscorp men. Or Farlan could have climbed from the engine deck and done it while Stein was in the airlock. Whoever it was, he had chosen to be locked in with the others--probably in case the sortie failed. Now they were two men short, and still he would have to pair off with Aron and pair Stein with Farlan. They would have to go on twelve-hour duty shifts, with only four hours free time. And to what purpose? As Tyruss had suggested several times, why couldn't they have just blasted The Egg out of space, if the purpose was to get rid of it? Why go to all the trouble of shifting it to an Earthward orbit? The Earth would be nowhere near the intersection point when The Egg reached Earth's orbit, if that made any difference. Jonner had at last let the others know, as he should have before, that one of them was a spy. But he would not tell them, as he had told Tyruss, that he had disconnected the radio transmitter. Let the spy try to get in touch with Marscorp now! * * * * * "Jonner," said Aron, "there are a couple of blips on the radar screen that shouldn't be there." Jonner swung the control chair to look at the screen. There were two dots there, almost directly to the rear of the spaceship. Jonner watched them. They held their position on the screen.