Before they had gone half a mile, they were sweating profusely and their arms and shoulders ached under their burden. Larkwell walked silently, steadily, but his breath was becoming a hoarse pant in Crag's earphones. The thought came to Crag that they wouldn't make it if, by any chance, Nagel failed to meet them. But he can't fail--not with Prochaska guiding them, he thought. They reached the end of the rill and stopped to rest. Crag checked his oxygen meter. Not good. Not good at all, but he didn't say anything to Larkwell. The construction boss swung his eyes morosely over the plain and cursed. "Nine planets and thirty-one satellites in the Solar System and we had to pick this dog," he grumbled. "Gotch must be near-sighted." Crag sighed and picked up his end of the stretcher. When Larkwell had followed suit they resumed their trek. They were moving around the base of a small knoll when Larkwell's foot struck a pothole in the ash and he stumbled. He dropped the end of the stretcher in trying to regain his balance. It struck hard against the ground, transmitting the jolt to Crag's aching shoulders. He lowered his end of the stretcher, fearful the plow had damaged the injured man's helmet. Larkwell watched unsympathetically while he examined it. "Won't make much difference," he said. Crag managed a weak grin. "Remember, we're angels of mercy." "Yeah, carrying Lucifer." The helmet proved intact. Crag sighed and signaled to move on. They hoisted the stretcher and resumed their slow trek toward the Aztec. Crag's body itched from perspiration. His face was hot, flushed and his heart thudded in his ears. Larkwell's breathing became a harsh rasp in the interphones. Occasionally Prochaska checked their progress. Crag thought Nagel was making damned poor time. He looked at his oxygen meter several times, finally beginning to worry. Larkwell put his fears into words. "We'd better drop this character and light out for the Aztec," he growled. "We're not going to make it this way." "Nagel should reach us soon." "Soon won't be soon enough." "Nagel! Get on the ball," Crag snapped curtly into the interphones. "Moving right along." The oxygen man's voice was a flat imperturbed twang. Crag fought to keep his temper under control. Nagel's calm was maddening. But it was their necks that were in danger. He repressed his anger, wondering again at the wisdom of trying to save the enemy crewman. If he lived?