The Martian was wide awake enough to realize his helplessness. He promptly pulled the desired key out of his pocket and handed it to Taggert. Robert covered the Martian with the automatic while Taggert fitted the key to the anklet. A moment later he was free. They were now faced by the problem of binding and gagging the conscious Martian. No rope was available within the tent. “His shirt,” suggested Robert, following his inspiration by pulling the garment off the now completely cowed Martian. Swiftly they bound, gagged and blindfolded him, the twisted arms of the shirt making fair substitutes for cord, though there was not enough to bind him as thoroughly as they wished. They locked the anklet upon him after shortening the chain by twisting and knotting it round the big center-pole. The unconscious Martian they left as he was. Warning the bound Martian with dire threats, they slipped out of the tent into the night. Had Phobus been shining then they would surely have been seen at once; but the little Martian moon had set an hour past. Creeping painfully past the clustered tents they came at last to the edge of the camp, which, fortunately, was not a great distance away. Here it was necessary for them to pass the pickets. The brilliant starlight and level, open desert made their escape extremely difficult. How far apart the pickets were stationed they did not know, but one paced slowly across a stretch just ahead of where they lay partly concealed in a slight depression or wave in the desert’s floor. Cautiously they wormed forward to another shallow depression while the near-by sentry’s back was turned. Here they waited anxiously as he paced back and again turned away. One thing in their favor for the present was that the sentry directed his attention chiefly in the opposite direction, toward the city. That would become their disadvantage, however, when once they succeeded in getting past the sentries and between them and the city. No sooner had the sentry turned his back again than they were scrambling feverishly toward a distant, faint strip of shadow, which indicated their next scanty haven of temporary safety. Their arms and knees were weary to the point of exhaustion; but they pressed on desperately. Still the little line of shadow ahead seemed far away. Would they make it before the sentry turned and discovered them? Surely he would notice the track where they had pawed their way through the loose sand. How they finally reached their goal neither could remember. It seemed that they had crawled and crawled for eternity--a sort of dreadful nightmare in which their limbs moved unwillingly while they remained in the same spot. Both were exhausted when they slid stiffly into the scanty haven of the little dip in the sand. For the moment they cared not whether they were captured or not. They longed only to lie panting till their parched throats had cooled.