Chet saw a blot of black figures at the top of the slope just as they felt firm ground beneath their feet. They followed where Towahg led in a swift race across the open arena toward the great steps at the rear. Black and white in strongly contrasting bands, the rock reared itself in a barrier that, to Chet, seemed hopelessly unsurmountable. He felt that they had come to the end of their tether. "Trapped!" he told himself, and wondered at Towahg's leading them into such a cul-de-sac, even while he knew that retreat in other directions was cut off. The pursuit was gaining on them; savages from beyond the pyramid had sighted them now in the full light of Earth, and their yelping cry came mingled with hoarse growls as the full pack took the trail. Ahead of them, Towahg, reaching the base of the first white step, was dancing with excitement beside a narrow cleft in the rocks. He led the way through the small passage. And Harkness, bringing up the rear, took the detonite pistol in his hand. "One shell! We'll have to waste it!" he said, and raised the weapon. Its own explosion was slight, but the sound of the bursting cartridge when its grain of detonite struck the rocks made a thunderous noise as it echoed between the narrow walls. "That will check the pursuit," Harkness exulted; "that will make them stop and think it over." * * * * * It was another hour before Towahg slackened his pace. He had led them through jungle that to them seemed impassable; had shown them the hidden trails and warned them against spiked plants whose darts were needle sharp. At last he led them to a splashing stream where they followed him through the trackless water for a mile or more. The mountain with the white scar was their beacon. Harkness pointed it out to their guide and made him understand that that was where they would go. And, when night was gone, and the first rays of the rising sun made a quickly changing kaleidoscope of the colorful east, they came at last to a barren height. Behind them was a maze of valleys and rolling hills; beyond these was a place of smoke, where red fires shone pale in the early light, and set off at one side was a shape whose cylindrical outline could be plainly seen. It caught the first light of the sun to reflect it in sparkling lines and glittering points, and every reflection came back to them tinged with pale green, by which they knew that the gas was still there. Chet turned from a prospect that could only be depressing. His muscles were heavy with the poisons of utter fatigue; the others must be the same, but for the present they were safe, and they could find some position that they could defend. Towahg would be a valuable ally. And now their lives were ahead of them--lives of loneliness, of exile. * * * * *