He moved the few steps into the small air-chamber which was the first of the three pressure locks. Its interior door-panel swung open for him. But the door did not close after him! Cursing the duty-man's slowness, he waited a few seconds. Then he turned to the corridor. The duty-man came running. Grantline took off his helmet. "What in hell--" "Broken! Dead!" "What!" "Smashed from outside," gasped the duty-man. "Look there--my tubes--" The control-tubes of the portes had flashed into a close-circuit and burned out. The admission portes would not open! "And the pressure controls smashed! Broken from outside--!" There was no way now of getting out through these pressure-locks. The doors, the entire pressure-lock system, was dead. Had it been tampered with from outside? As though to answer Grantline's amazed question there came a chorus of shouts from the men at the corridor windows. "Commander! By God--look!" A figure was outside, close to the building! Clothed in suit and helmet, it stood, bloated and gigantic. It had evidently been lurking at the porte-entrance, had ripped out the wires there. It moved past the windows, saw the staring faces of the men, and made off with giant bounds. Grantline reached the window in time to see it vanish around the building corner. It was a giant figure, larger than a normal Earthman. A Martian? * * * * * Up on the summit of the crater the two small figures were still fighting. All this turmoil had taken no more than a minute or two. A lurking Martian outside? The brigand, Miko? More than ever, Grantline was determined to get out. He shouted to his men to don some of the other suits, and called for some of the hand bullet projectors. But he could not get out through these main admission portes. He could have forced the panels open perhaps; but with the pressure-changing mechanisms 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.