Gray was up and running again. He knew the way into the explored galleries. From there on, it was anybody's guess. Caron was brazen enough about it. The subtle way had failed. Now he was going all out. And he was really quite safe. With the broken cables to act as conductors, the first thunderstorm would obliterate all proof of his activities in this valley. Mercury, because of its high electrical potential, was cut off from communication with other worlds. Moulton, even if he had knowledge of what went on, could not send for help. Gray wondered briefly what Caron intended to do in case he, Gray, made good his escape. That outpost in the main valley, for which Ward had been heading, wasn't kept for fun. Besides, Caron was too smart to have only one string to his bow. Shouts, the spatter of shots around them. The narrow trail loomed above. Gray sent the girl scrambling up. The sun burst up over the high peaks, leaving the black shadow of the valley still untouched. Caron's ship roared off. But six of its crew came after Gray and Jill Moulton. * * * * * The chill dark of the tunnel mouth swallowed them. Keeping right to avoid the great copper posts that held the cables, strung through holes drilled in the solid rock of the gallery's outer wall, Gray urged the girl along. The cleft his hand was searching for opened. Drawing the girl inside, around a jutting shoulder, he stopped, listening. Footsteps echoed outside, grew louder, swept by. There was no light. But the steps were too sure to have been made in the dark. "Infra-red torches and goggles," Gray said tersely, "You see, but your quarry doesn't. Useful gadget. Come on." "But where? What are you going to do?" "Escape, girl. Remember? They smashed my ship. But there must be another one on Mercury. I'm going to find it." "I don't understand." "You probably never will. Here's where I leave you. That Martian Galahad will be along any minute. He'll take you home." Her voice came soft and puzzled through the dark. "I don't understand you, Gray. You wouldn't risk my life. Yet you're turning me loose, knowing that I might save you, knowing that I'll hunt you down if I can. I thought you were a hardened cynic." "What makes you think I'm not?" "If you were, you'd have kicked me out the waste tubs of the ship and gone on. You'd never have turned back." "I told you," he said roughly, "I don't kill women." He turned away, but her harsh chuckle followed him. "You're a fool, Gray. You've lost truth--and you aren't even true to your lie." He paused, in swift anger. Voices the sound of running men, came up from the path. He broke into a silent run, following the dying echoes of Caron's men. "Run, Gray!" cried Jill. "Because we're coming after you!"