Several years ago--ten, twenty, perhaps more--some doctor had finally isolated a strain of the filterable virus of liguna fever that could be used as a vaccine: too weak to kill, but strong enough to produce immunity against its more virulent brother strains. That opened up the Sitari System for colonization and exploration and meant that the men who got there first would make fortunes. So he went to the base at Ke, first selling his strip mine property and disposing of his tools and equipping his spaceship for the intersolar trip; and at Ke they shot him full of the disease. But his bloodstream built no antibodies. The weakened virus settled in his nervous system and there was no way of getting it out. The doctors were very sorry for him, and they assured him it was a one-in-ten-thousand phenomenon. Thereafter, he suffered recurrent paralytic attacks. If it had not been for the advance warning--a pain at the base of his spine, a moment of violent trembling in his knees--he would have been forced to give up solitary strip mining altogether. As it was, whenever he felt the warning, he had to hurry to the nearest colony and be hospitalized for the duration of the attack. He had had four such warnings on this satellite, and three times he had gone to Pastiville on Helio and been cared for and come away with less money than he had gone with. His bank credit, once large, had slowly dribbled away, and now he made just about enough from his mining to care for himself during illness. He could not afford to hunt for less dangerous, less isolated work. It would not pay enough, for he knew how to do very little that civilization needed done. He was finally trapped; no longer could he afford a pilot for the long flight from Helio to a newer frontier, and he could not risk the trip alone. He lay waiting for the new spasm of fever and stared at Hertha who, this time, would care for him here and he would not need to go to a hospital. Perhaps, after a little while, he would be able to save enough to push on, through the awful indifference of space, to some new world where, with luck, there would be a sudden fortune. Then he could go back to civilization. He realized bitterly that he was merely telling himself he would go back. He knew there was only one direction he could go, and that direction was not back. Hertha waited, hurt-eyed, moving her pudgy hands helplessly. When the shaking subsided, he explained through chattering teeth about the oxygen register across the room, and she went away. * * * * * The fever vanished completely, leaving him listless. His hand, lying on the rough blanket, was abnormally white. He wiggled the fingers, but he could not feel the wool. His mouth was dry and he wanted a drink of water. Hertha moved out of his range of vision. He shifted his head on the damp pillow and watched her out of the corner of his eye.