Greg took quick stock of the cabin again. Then he took a deep breath and bellowed, "Johnny ... _duck_!" Almost by reflex, Johnny Coombs hurled himself to the floor. Tawney swung the gun around. There was an ugly ripping sound as the stunner fired ... but Greg was moving by then. In two bounds he was at the control panel. He hooked an arm around a shock bar, and slammed the drive switch on full. There was a roar from below as the engines fired. Greg felt a jolt of pain as the accelleration jerked at his arm. Tom and the Major were slammed back against a bulkhead, then fell in a heap on top of Johnny and the Lieutenant as the awful force of the accelleration dragged them back. Across the cabin Tawney sprawled on the floor. The stunner flew from his hand and crashed against the rear bulkhead. On the panel Greg could see the accelleration gauge climbing swiftly ... past four g's, up to five, to six. The ship was moving wildly; there was no pilot, no course. With all the strength he could muster Greg tightened his arm on the shock bar, lifting his other arm slowly toward the cut-off switch. He had spent many hours in the accelleration centrifuge at Star-Jump, learning to withstand and handle the enormous forces of accelleration for brief periods, but the needle was still climbing and he knew he could not hold on long. His fingers touched the control panel. He strained, inching them up toward the switch.... His fingers closed on the stud, and he pulled. The engine roar ceased. On the floor behind him Tawney moved sluggishly, trying to sit up. Blood was dripping from his nose. He was still too stunned to know what had happened. Greg leaped across the room, caught up the stunner, and then sank to the floor panting. "All right," he said as his breath came back, "that's all. Your ship may have trouble finding us now ... but I bet our pilot can get us back to Mars." * * * * * When they left the Sun Lake City infirmary it was almost noon, and the red sun was gleaming down from overhead. Walking slowly, the Hunter twins moved along the surface street toward the U.N. building. "He'll recover without any trouble," the doctor had assured them. "He caught the stunner beam in the shoulder, and it will be a while before he can use it, but Johnny Coombs will be hard to keep down." They had promised Johnny to return later. They had had check-ups themselves. Both Tom's eyes were surrounded by purple splotches, and his broken left arm was in a sling. Greg's arms and legs were so stiff he could hardly move them. The Major and the Lieutenant had been sore but uninjured. Now the boys walked without talking. Already a U.N. linguist was at work on the record tapes from the metal cylinder, and a mathematician was doing a preliminary survey on the math symbols on the metal block. "I hope there's no trouble reading them," Greg said.