Now he jumped out of bed and examined the fastening of his door, the door to the hotel corridor. There was only one, and it was secure. Windows there were none, and investigation showed that the small ports were all covered with their pivoted safety plates. He extinguished the light, swung aside one of the plates, and peered out into the Martian night. It was moonlight--both Deimos and Phobos were racing across the blue-black sky. The waters of Crystal Canal stretched out before him, seemingly illimitable. Sime knew that the distance to the other side was twenty miles or more. Clear-cut through the thin atmosphere of Mars, he could see the jeweled lights of South Tarog, on the other side. * * * * * The hotel grounds, too, were well lighted. Long, luminous tubes, part of the architecture of the buildings, aided the moons, shedding their serene glow on the gentle slope of the red lawns and terraces, the geometrically trimmed shrubs and trees. They were reflected warmly in the dancing waves of the canal, though Sime knew that even in this, the height of the summer season, the outside temperature was very near freezing. Now a hotel guard came along. He carried at his belt a neuro-pistol, a deadly weapon whose beam would destroy the nervous structure of any living creature. He went past the port with measured stride, and Sime slid back the safety plate with a puzzled frown. Why was he so nervous? This wasn't the first dangerous mission on which he had embarked in the course of his official duty. And danger was the element that gave zest to his life. [Illustration: Clinging like leeches to the wall, the two men resisted the warped gravitational drag.] He began a methodical examination of his room, peering under the bed, into closets, a wardrobe. Yet there was no sign of danger. Carefully he inspected his bed for signs of the deadly black mold from Venus that would, once it found lodgment in the pores of a man's skin, inexorably invade his body and in the space of a few hours reduce him to a black, repulsive parody of humanity. But the sheets were unsullied. Then his gaze fell on the mist-bath. Travelers who have visited Mars are, of course, familiar with this simple device, used to overcome to some extent the exceeding dryness of the red planet's atmosphere. Resembling the steam bath of the ancients, there was just enough room in the cylindrical case for a man to sit inside while his skin was sprayed with vivifying moisture. But his head would project, and there was no head visible. Nevertheless, so strong was Sime's intuition, he leveled his neuro-pistol at the cabinet and approached. With a sweep of his muscular arm he swung it open--and gasped! * * * * *