All at once, a crack appeared in Keifer's helmet, running from crown to chin. Alan struck again with his right fist. The crack became a hole. Keifer opened his mouth to scream, but then his face was swelling, bloated--became a shapeless thing which no longer could fit within the helmet. Trembling, Alan stood up and rushed to the control. He saw that Laura was already heading the moon tank back toward the launching platform. He had a few seconds in which to play.... The tank lurched to a stop beside the platform. * * * * * Hand over hand, Alan was climbing the scaffold. He reached the platform with the tank's atomic rifle strapped across his shoulders. Half a dozen technicians were preparing to leave. "Shut it off!" Alan shouted. "Don't launch that bomb!" "We can't stop it now. The mechanism is set." "I'll kill you if I have to." "We can't, don't you understand? The bomb will be launched in five minutes--no, four minutes and fifty seconds now. Once set, it's fully automatic. We didn't want to set it. Keifer made us do it. You're Alan Tremaine, aren't you?" the technician asked. "We're on your side, Tremaine. Most of the Outworlds are, ever since Earth's broadcast. But Keifer came here with a hard core of his followers in a small fleet and--" "Never mind the talk. Can't you render the bomb harmless?" The technician shook his head within the glassite helmet. Overhead, the quarter-phase Earth was shining brightly, waiting helplessly. "It's the radioactive cobalt that will do the damage," Alan said. "An atomic trigger for the hydrogen bomb, a hydrogen trigger for the cobalt, right?" "Essentially, yes." "Then strip off the cobalt, you fools!" "Three minutes," someone said. "We've got to get out of here. The after-burners of the launching charge will cremate us." "It can be done," one of the technicians told Alan, "but I don't think you have the time." "How, man? Tell me how!" "Use your rifle. There's a seam running around the bomb. See? See it. If you can cut around the whole seam, the cobalt should fall away in two hemispheres. A hydrogen bomb alone would be launched at Earth, but it should fall harmlessly into the Pacific Ocean." "Two minutes, forty seconds." The technicians moved about uneasily. Two of them began to climb down the scaffold. The rest remained to watch Alan. They would save the Earth or perish with him. Alan raised his atomic rifle to his shoulder, aimed at the thin welded seam about the huge bomb, and began to fire. At first there was nothing. The pellets hit the bomb, which could only be triggered by an atomic implosion at its core, and exploded there. "A minute and a half," someone said, his voice hoarse over Alan's suit radio. The seam was widening, became a gap a foot across. Alan continued firing, the rifle slapping back against his numb shoulder. The crack spread around the circumference of the bomb. "One minute to blast-off!"