The inventor pulled off his smock and threw it over the materials on his work bench, so that the person at the other end of the view-phone connection, whoever it was, would not be able to see them. Then he snapped the television and audio switches. The mists in the view-plate cleared, and there before him, as real as though he were actually in the room, sat Hekalu Selba. The Martian's eyes gleamed with suppressed excitement. "Mr. Shelby," he was saying, "it may seem strange that I should be calling you so soon, but I have something simply colossal to talk over with you. You must come up to my place immediately! I realize that you may be very busy, but this _is_ important!" And he added, "It's nothing to discuss over the view-phone. Will you come?--please!" Shelby was about to make a cold reply, but he checked himself. An intense curiosity gripped him. "All right, Akar Hekalu," he said. "I'll be there." The switches clicked. Hastily Austin changed to his street clothes, and then gathered together the material for his weapon and placed them in the wall safe. Only one thing he selected from the jumble of apparatus--a tiny pinkish crystal, without which it was impossible to produce the Atomic Ray. This he secreted in a hollow button on his sleeve. For a long moment he stared at his automatic, which lay on his work bench. "Better take you along," he muttered at length, "--may need you." A wizened black-clad man whom Shelby surmised was the slave Alka, met him at the entrance on the landing platform of a quaint Martian tower atop a huge apartment building, and ushered him into an elevator. He was whisked rapidly downward, and emerged into the central light-well which pierced the structure from top to bottom. The barbaric tapestries upon the walls of this tall cylindrical chamber, the tiling of the floor, which consisted of squares and circles and spear points of various colored stone, fitted artfully together, giving an effect of pleasant disorder. And most of all, the smell of strange incense in the air, told Shelby that he had dropped into a little bit of old Pagar or Mars. Evidently the Prince of Selba was master of the entire tower, which, in itself, was by no means small. Alka led the way down a short passage, and admitted the Earthman to a large sumptuously furnished room, one end of which was softly illuminated by a quaintly beautiful floor lamp. The farther end of the room was in complete darkness. The Pagarian architects had made it imitate the interior of a natural cavern, for where the light approached the gloom, two glassy stalactites gleamed with a scintillant elfin light.