Psychiatrist Doctor Hill (Whit Bissell) is in the emergency room of a hospital in California. A screaming man tells the following story. Doctor Miles Bennell (Kevin McCarthy), in Santa Mira, California, sees several patients suffering from Capgras Delusion—the belief that their relations have been replaced by duplicates. His girlfriend Becky Driscoll (Dana Wynter) says her cousin Wilma (Virginia Christine) had made the same complaint about her Uncle Ira (Tom Fadden). Psychiatrist Doctor Dan Kauffman (Larry Gates) says this is only an epidemic of mass hysteria.

Miles and Becky are called to the home of Jack Belicec (King Donovan), who seems to have found a dead body. Strangely, the body has no facial features or fingerprints, but slowly comes to resemble Belicec himself. Then, a body duplicate of Becky is found in her basement. When they call Doctor Kaufmann, the bodies disappear. The next night, Bennell, Becky, Jack, and Jack’s wife Teddy (Carolyn Jones) find duplicates of themselves emerging from giant pods in Bennell’s greenhouse. Bennell tries to call the authorities, but the operator claims that the long-distance lines are all busy. The next morning, it seems the whole town has been replaced. They see trucks full of giant pods arriving in town, Chief of Police Nick Grivett (Ralph Dumke) directing their distribution.

Kaufmann and Belicec, both pod-people now, arrive at Bennell’s office with new pods for him and Becky. They reveal that this is an extraterrestrial invasion. Once all the humans have been replaced, the world will be calm and stress-free, with no pesky emotions to cause trouble. Bennell and Becky knock out the aliens and escape. They pretend to be emotionless in the street, but Becky screams when a dog runs into traffic. The alarm is sounded, and they are pursued by pod-people.

They hide in an abandoned mine, struggling to stay awake, but Bennell leaves to check out some lovely music, which turns out to be just the radio, and when he returns, he finds to his horror that Becky has fallen asleep and is taken over. She sounds the alarm, and he runs, chased by the mob. On a crowded highway, he sees pods on route to other cities and screams at the passing motorists, “You’re next!” Back at the hospital, Bennell finishes his story. Doctor Hill believes he is psychotic, but a truck-driver comes in on a gurney, having been crushed by a load of giant pods. Doctor Hill calls the FBI.

The movie was directed by Don Siegel, who directed John Wayne’s The Shootist and five movies by Clint Eastwood, and it was produced by Walter Wanger. Daniel Mainwaring adapted the screenplay from a 1954 SF novel by Jack Finney. The novel had a happy ending, with the aliens leaving altogether, but the movie was all film noir and paranoia. Sam Peckinpah had a cameo as a meter-reader. Originally to be called The Body Snatchers after the novel, it might have been confused with a Val Lewton film called The Body Snatcher. After five other choices were tried, it was finally given its present title. The producer tried to get Orson Wells to read the introduction with Winston Churchill’s words but was unable to do so. Then he tried to get Ray Bradbury to write an intro, but that didn’t happen either. The prologue and epilogue were an attempt not to be too depressing.

Papier maché pods were placed in theater lobbies. Some reviewers thought the film was a lesson about McCarthyism, while others thought it was a warning about Communism. Actor Kevin McCarthy and story-writer Jack Finney insisted there was no political meaning whatsoever. Critics pretty much ignored it, but now it is beloved and considered important. It is in the Library of Congress as a cultural icon. Looney Toons created a short, entitled Invasion of the Bunny Snatchers. Kevin McCarthy once left a pod on Dana Wynter’s front porch.

For the creation of the pods, the actors had to wear skin-tight latex, breathe through straws, and be submerged in hot casting material. There were complaints about nudity but there was none. Kevin McCarthy was injured from running so much. He was so exhausted that he could have been hurt running into traffic for the last sequence. Originally, there was humor in the film and the audience laughed and shrieked in terror by turns, but the head of the studio demanded to know why people were laughing at his horror movie, and the humor was cut out to please the humorless pod-people in charge of the studio.