In a futuristic world, Chuck Browning, a newspaper reporter, gets a telephone call from Frenchy, a man who claims to have information about a scandal regarding a resort called Delos that is “peopled” by robots. Upon meeting, Chuck finds Frenchy bleeding to death, but retrieves a file of news clippings. Days later, Chuck attends a press conference held by Delos to promote the resort. Chuck sits next to television reporter Tracy Ballard as the resort’s representative, Duffy, recalls that the Delos robots malfunctioned a few years back and massacred all the guests. Perturbed by Chuck’s presence, Tracy becomes distracted by television monitors showing a bald gunfighter shooting people in the “Westworld” section of the park. Duffy informs the press that the redesigned park has opened, but only to tepid results. Therefore, select members of the press are invited to the resort for a weekend to demonstrate the park’s safety. Later, Tracy complains to her boss that he promised her an exclusive on the Futureworld story, but Arthur explains that Chuck is working on a different angle. Later, Chuck apologizes to Tracy for firing her right after they slept together when she was a print reporter. He cajoles her into a truce, promising her the television exclusive of his story. Later, Chuck and Tracy fly to Delos with the other guests, including: Mr. Karnovski, a Russian general traveling with his wife; Mr. Takaguchi, a wealthy electronic manufacturer, and his aide; and Ron Thurlow, winner of a game show. Arriving at Delos, the guests are transported to the “worlds” they have selected. The elderly Karnovskis go to the fountain of youth, where they will relive their courting in Czarist Russia. Takaguchi picks “Medieval World,” where he will be a knight. Tracy, Chuck, and Ron select “Futureworld,” a satellite resort orbiting Mars. Duffy informs that Tracy she will command the “flight” and the trio are led to a rocket, where they blast off to the station. In a large control room, Duffy watches the guests on monitors with Dr. Schneider, the resort director. After assuring himself that everything is going according to plan, Schneider goes to another control room where technicians film and measure Chuck, Tracy, Karnovski and Takaguchi’s face and bodies. On the space station, Chuck shows a robotic bartender a picture of Frenchy, but the bartender claims to have never met him. When Duffy arrives to ask if they would like a peek behind the scenes, Chuck asks the bartender to return the photograph, but the robot insists he already returned it. Duffy leads Tracy and Chuck into the control center where they view Takaguchi winning a jousting tournament on a screen. Chuck notices the intensity of the technicians as they monitor the guests, and Duffy explains that all the technicians are robots. In an effort to eliminate human error, very few people work at Delos. Duffy then takes the reporters to the abandoned “Westworld.” While exploring alone, Chuck finds a hatch leading to the tunnels beneath the park. When Tracy comes looking for him, Chuck scares her with a detached robotic arm. Infuriated, she returns to their quarters, warning him not to attempt to sleep with her. That night, Chuck, Tracy, Karnovski, and Takaguchi are drugged and brought to a lab where they are molecularly examined by technicians. They are returned to their beds, and Tracy later wakes up screaming from what she believes to be a nightmare. When Chuck comforts her, she notices he is dressed. When he explains he is going exploring, she insists on joining him. Sneaking through the tunnels, they find the research and development area where they accidently activate a machine that materializes three sword wielding Chinese warriors, who chase them. They are saved when Harry, a human groundskeeper, turns off the robots. Harry leads them out of the chamber before Dr. Schneider and the security guards arrive. In his private area, Harry introduces them to Clark, a primitive robot with no face. Chuck discovers that Harry knew Frenchy, but Schneider arrives and asks them to leave. Back at their quarters, Chuck and Tracy study Frenchy’s press clippings, covering world leaders who visited Delos. Chuck is convinced Harry can help him find out what Frenchy was trying to communicate. Tracy is afraid they will be thrown out if they break any more rules, but agrees to help Chuck. The next day, Duffy shows the reporters the “space chamber,” a machine that records electrical impulses during dreams and converts them into images. Tracy volunteers to try it and, after she falls asleep, dreams she is running through an empty mansion, pursued by the technicians. She spots the Gunfighter from Westworld, then finds herself strapped to a table with the technicians preparing to cut her. The Gunfighter shoots the technicians, and then dances with her. Before they make love, she wakes up. Meanwhile, Chuck sneaks off to find Harry playing cards with Clark and informs Harry about Frenchy’s murder. Harry brings Chuck to a chamber off limits to humans. Even with the keypad code, the door only opens for robots. Realizing there must be a retina scanner detecting robots’ circuitry, Harry ambushes a robot, removes the face, and attaches it to a welder’s mask. When Tracy joins them, Harry dons the mask and stares into the keypad. The door opens and inside are doubles of Karnovski, Takaguchi, Tracy, and Chuck being programmed to take their places. The three rush to collect their belongings, and agree to rendezvous in Westworld before catching the next flight out of Delos. In their quarters, Tracy packs as Chuck tries to call his editor, but press secretary Duffy appears holding a ray gun and explains that world leaders are being replaced with replicas, programmed to dominate the human race. Duffy takes aim, but Tracy hurls a suitcase from above. Duffy drops the gun and Chuck wrestles with him until Tracy retrieves the weapon and, kills Duffy, who turns out to have been a robot. Harry says goodbye to Clark, promising he will return for him, then rushes into the tunnel where he runs into Chuck’s replica, which stabs him to death. The real Chuck and Tracy go to Westworld, but when Harry does not arrive, Chuck searches for him and arrives in time to see his own double standing over Harry’s body. Meanwhile, Tracy comes face to face with her duplicate. They square off and fight with the ray guns. One of the two drops to the ground and the other looks for Chuck. Chuck’s replica chases him up the Futureworld launching tower. Chuck spots a high voltage box and uses it to electrify a piece of the catwalk, but the duplicate Chuck avoids the trap. A gunfight ensues until both run out of ammunition. The two fight hand to hand until one is pushed to his death. Chuck and Tracy find each other but have no way of knowing if either of them is a replica. Chuck kisses Tracy. When Schneider blocks the resort’s exit, Tracy says they had a wonderful time and that she cannot wait for her television special on Delos. Chuck also promises to write a good story. Satisfied they are the replicas, Schneider allows them to leave, only to have the duplicate Tracy appear. Schneider has made a mistake. Chuck turns, sees the duplicate Tracy and taunts Schneider the vulgar extension of his middle finger. At the airport, Chuck tells Tracy he got through to Arthur and their story is already being reported. Tracy tells him a kiss is an unscientific means of identification, but Chuck says there are just some things that cannot be faked.