Sometime in the near future a high-tech, highly realistic adult amusement park called Delos features androids that are almost indistinguishable from human beings. For $1,000 per day, guests may indulge in any fantasy, including killing or having sex with the androids. Delos' tagline in its advertising promises "Have we got a vacation for you!" The androids are programmed to act in character for each of the park's three themed "worlds" — WestWorld (the American Old West), MedievalWorld (medieval Europe), and RomanWorld (pre-Christian Rome). One of the attractions in WestWorld is the Gunslinger (Brynner), a robot programmed to start duels.