The fog closed in. Silver mist veiled the strange, ghostly forest. Then it was torn away as a gust of wind drove down from the upper air. Above, the clouds twisted in tortured writhings; but Vanning did not look up. Not once did he turn his head. He faced north ... he plodded north ... he slogged through mushy, stinking swamp that rose at times to his waist.... A sane man would have skirted the bog. Vanning floundered across, and swam when he could no longer walk. Somewhere to the left he heard the coughing mutter of a swamp-cat's engine, but he did not see the machine. His vision was restricted to a narrow circle directly ahead. Dimly he felt pain. The clinging, soft nettles of Venus ripped at his clothing and his skin. Leeches clung to his legs till they fell off, satiated. Vanning went on. He was a robot--an automaton. In silence the pale forest slipped by in a fantastic procession. Lianas often made a tangled snare where Vanning fought for minutes before breaking through. Luckily, the vines had little tensile strength, but soon the man was exhausted and aching in every limb. Far above, the clouds had thickened and darkened into what passed for night on fog-shrouded Venus. But the trees gave a phosphorescent light of their own. Weird beyond imagination was the scene, with the bloody, reeling figure of the man staggering on toward the north-- North. Ever north. Until overtaxed muscles refused to bear the burden longer, and Vanning collapsed into exhausted unconsciousness. He did not know when he awoke. Presently he found himself walking again. Nothing had changed. The jungle was denser, and the cool light from above filtered down once more. Only the light was cool. The air itself was sticky and suffocating. He went on into hell. Days and nights merged into a fantastic pattern of dull torture. Some distantly sane portion of his brain held back and watched, but could not help. Days and nights. There was no food. There was water, for as Vanning splashed through shallow pools he would bend his head to drink of the foul liquid. Once his feet crunched on the green-moulded bones of a human skeleton. Others had taken this way before him.... * * * * * Toward the end, a fleshless, gaunt thing that had once been a man dragged itself laboriously toward a range of mountains that lifted from the swamp toward the north. They extended to left and right as far as he could see, and seemed unscalable. But they were V-shaped, and Vanning headed toward the point of the V--the inner point. The terrible drive within him drove him on relentlessly. That night a sulphurous crimson glow lit the sky beyond the mountains. Vanning did not see it. He slept. By morning he was on his way again, staggering into the funnel of the peaks. They were bare rock, eroded by eons of trickling water from the clouds. He could not climb them, even had he possessed the strength. He went on, instead, into the narrowing valley....