The film attempted to take the plot in a different direction from the Westworld movie, but it was not generally well-received by the critics. The film was deemed as lacking in action and the acting was not engaging. It was made by AIP (its predecessor was made by Metro-Goldwyn-Mayer, which later bought AIP's successor Orion Pictures).
After some investigation, the two reporters discover that Delos' entire resort is simply a ruse to attract world leaders, the rich, and the famous for a sinister plot. Guests are drugged during their stay through one of their meals (as happens to Browning and Ballard), and during this state of unconsciousness, genetic samples are taken. From the extensive genetic sampling, Delos technicians create fully programmed engineered clones who, with murderous intent, replace the wealthy and influential visitors - thereby allowing Delos to take over the world. As the owner of Delos, Dr. Duffy (Arthur Hill), explains that if it is left alone, the planet would be destroyed by the end of the decade. "We at Delos have no intention of being destroyed by you" he adds. The clones will run the world under Delos control and end political directions the leaders of Delos find threatening. The two reporters are selected for early termination and replacement, but Browning discovers this fact in time. This results in a dramatic chase and battle between the reporters and their doubles.
Having successfully dispatched their twins, the duo make their way to Delos’ airport. Before leaving they come across the project's chief scientist and tell him that they plan to return to the outside world with “glowing reports” of the new resort – just as planned.
However, just as they reach the busy departure lounge, and much to the surprise of the chief scientist, one of the battered and dying evil clones staggers into view claiming “They’re the wrong ones….”, before slumping to the floor. Exasperated, the chief scientist looks on as Browning flips him the bird and walks to safety, as we hear that the story has been successfully broken to the world.