But he could not get out through these main admission ports. He could have forced the panels open perhaps; but with the pressure changing mechanism broken, it would merely let the air out of the corridor. A rush of air, probably uncontrollable. How serious the damage was, no one could tell as yet. It would perhaps take hours to repair it. Grantline was shouting, "Get those weapons! That's a Martian outside! The brigand leader, probably! Get into your suits, anyone who wants to go with me! We'll go by the manual emergency exit." But the prowling Martian had found it! Within a minute Grantline was there. It was a smaller two-lock gateway of manual control, so that the person going out could operate it himself. It was in a corridor at the other end of the main building. But Grantline was too late! The lever would not open the panels! Had someone gone out this way and broken the mechanisms after him? A traitor in the camp? Or had someone come in from outside? Or had the skulking Martian outside broken this lock as he had broken the other? The questions surged on Grantline. His men crowded around him. The news spread. The camp was a prison! No one could get out! And outside, the skulking Martian had disappeared. But Wilks and Haljan were still fighting. Grantline could see the two figures up on the observatory platform. They bounded apart, then together again. Crazily swaying, bouncing, striking the rail. They went together in a great leap off the platform onto the rocks, and rolled in a bright patch of Earthlight. First one on top, then the other. They rolled unheeding to the brink. Here, beyond the midway ledge which held the camp, it was a sheer drop of a thousand feet, on down to the crater floor. The figures were rolling; then one shook himself loose; rose up, seized the other and, with desperate strength, shoved him-- The victorious figure drew back to safety. The other fell, hurtling down into the shadows past the camp level--down out of sight in the darkness of the crater floor. Snap, who was in the group near Grantline at the window gasped, "God! Was that Gregg who fell?" No one could say. No one answered. Outside, on the camp ledge, another helmeted figure now became visible. It was not far from the main building when Grantline first noticed it. It was running fast, bounding toward the spider staircase. It began mounting. And now still another figure became visible--the giant Martian again. He appeared from around the corner of the main Grantline building. He evidently saw the winner of the combat on the cliff, who now was standing in the Earthlight, gazing down. And he saw too, no doubt, the second figure mounting the stairs. He stood quite near the window through which Grantline and his men were gazing, with his back to the building, looking up to the summit. Then he ran with tremendous leaps toward the ascending staircase.