Beside the smaller port-lock's inner door a figure had appeared, clad in the neat yellow smock of a servitor of Ku Sui. It was a smooth, impassive Oriental face that turned to stare out at the approaching men; and even Ban knew that this sentinel stationed at the lock was one of the coolies whose brains Dr. Ku had altered, turning him into a mechanicalized man who obeyed no orders but his. He watched closely the three who swept on towards him, his hand at a raygun in his belt. The same questions were in the minds of all three of the raiders. Would he recognize something as being different, or suspicious? Would he summon others of his kind from the small guard-box he had come out of? But the coolie evinced no alarm. It would have been difficult for anyone to have discerned distinguishing features inside the cumbersome helmets, behind the instruments clamped to the faces of the men who wore the suits. He called no others, but merely watched. Soon the opaque metal plates of the small lock's outer door had neared to within a few feet of Hawk Carse, and he stopped short, Ban and Friday following suit. They hovered there outside the door, gently swaying like flies against the great gleaming sweep of the dome, the craggy rock face dropping sickeningly down for miles beneath them. And, like flies, they were powerless to open the door to gain entrance. Only the coolie inside could do that; and he, through the dome to one side, was peering at them. Apparently he was satisfied with his scrutiny. After a moment, bolts shifted and the door stirred and swung out, revealing the all-metal atmosphere chamber and the inner door at the far side. Immediately Carse floated into the chamber, and the two others pressed in behind. They saw the outer door swing shut, and heard its locks thud over. They were sealed from sight inside the port-lock's atmosphere chamber. "Looks to me," whispered Ban Wilson, "like a very sweet trap. If that fellow inside wants to--" The Hawk's cool voice cut him off. "We can take off the glasses now," he said casually. "Keep alert." And for a full minute they waited. * * * * * At length a circle of light showed around the rim of the inner door, and it grew quickly into the full flood of Jupiter-light as the door opened. Carse floated through, no longer attempting to avert his face. The coolie, standing just outside the chamber, saw the adventurer's features and remembered--and drew the raygun in his belt.