The Humanspace starship Vathek is damaged in a mysterious z-ray storm and crash lands on a barren planet with no sign of life. As repair of the badly damaged ship is considered likely impossible, the crew erects condenser units, rations protein pills and searches for a solution.
The science officer discovers that rare wavium crystals present in a network of caverns nearby could be used to repair the Vathek. A party from the ship is dispatched toward the caves and they encounter a series of what appear to be advertising signs written in an unknown alien language which lead them to their intended destination. Under tall palms, on a low lithium salt dune near the mouth of the cave stands a weird alien bazaar run by a space trader. The trader informs the party that he is sole local agent of Gidj and Sons, an interplanar mercantile corporation.
The trader materializes exotic and seemingly delicious foods, drinks and intoxicants from across known space. Subsequently, the trader repeats the performance creating a used Mark 50 interfogulator, a weather-controlling machine, an atomic bomb, other incredible super scientific devices and bizarre artifacts from other dimensions. It becomes apparent that the trader is capable of materializing almost anything, including vital equipment needed to repair the ship. Any attempt to touch the merchandise will result in the item vanishing, If the trader is attacked he instantaneously teleports to safety.
The trader will accept no ordinary payment for his wares. He will allow the party to sample the feast table or acquire certain lesser items (though nothing that would enable repair of the ship) in exchange for weapons, valuable equipment, or through other arrangements, such as having members of the crew agreeing to become his slaves.
The agent of Gidj and Sons informs the crew that he will trade the items that they need for certain treasures that may be found within the caves; unfortunately, the ship’s sensors inability to locate life on the planet was not the result of a system failure; the caves are teeming with the living dead.