THE MYSTERY OF DENEB IV By ROBERT SILVERBERG _When Dave Carter tried to rescue the Denebians he found himself in a den of thieves. And he had cause to remember Shakespeare's observation: "He who steals my purse steals trash."_ [Transcriber's Note: This etext was produced from Fantastic February 1957. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] The first thing that crossed Dave Carter's mind was that the SOS was some kind of hoax. Then a fist thudded into the back of his neck, and he knew it was worse than a hoax--it was a trap. His knees sagged and he grabbed wildly for the side of his spaceship. Steadying himself, he struck out with a fist. His unknown assailant grunted. Carter's eyes widened as he discovered he was fighting another Earthman, here on this alien world in the Deneb system. _What the devil is this?_ Carter asked himself, as his fist crashed into the other's stomach. _They ask me to come rescue them--and then they jump me from behind._ The man was wearing the gray-and-gold uniform of the missing _Vanguard_ expedition. He was a big, rangy spaceman. His eyes glittered with a cold menace that Carter had never seen in human eyes before. Carter reached back, grasped the rungs of the ladder behind him with both hands, and kicked out at the other. The man crumpled backward onto the ground. Carter ran over to him. He put a knee on the other's chest. "Who are you?" he demanded. No answer. "Why'd you send out an SOS?" Carter demanded. The other man glared coldly at him without replying. Carter pulled him to a sitting position and slapped him, twice, hard. "Answer me! You're from the _Vanguard_ expedition, aren't you?" "Yes." The voice sounded steely, metallic. "Then why'd you jump me? I picked up your SOS and came down here to rescue you! Answer me!" "You'll know the answers soon enough." Carter shook his head angrily. "I want to know right now. Where are the other members of the expedition?" "They are here. They are all safe." Pulling the other to his feet, Carter drew his blaster and said, "Suppose you take me to them--right now. I want some explanation of all this. Move!" * * * * * An hour before, Carter had been in space, traveling alone from the Base Hospital on Rigel IV toward Ophiuchus VII. He expected to spend his period of convalescence there. Ophiuchus VII was a low-grav world set aside as a vacation planet for recuperating invalids.