The aliens emerge from plantlike pods, and grow into perfect physical duplications of their human victims, who themselves die and are discarded. The "pod people" are indistinguishable from normal people, except for their utter lack of emotion. Once a pod person is fully grown and integrated into society, he works secretly to spread more pods, so that more people will be taken over.
The film is frequently cited as an indictment of the hysteria of McCarthyism during the early stages of the Cold War. The taking-over of ordinary citizens metaphorically reflected the paranoia in Cold War America of how communism might infiltrate the body politic in such a way that you would have no way of suspecting if your friends and neighbors had been corrupted.
The screenplay was adapted by Richard Collins (uncredited), Daniel Mainwaring and Sam Peckinpah from the novel The Body Snatchers by Jack Finney. It was directed by Don Siegel.
The first of two remakes appeared in 1978, starring Donald Sutherland, Brooke Adams, Jeff Goldblum and Veronica Cartwright. There are a number of interesting cameos in the film, among them the star and director of the original; Kevin McCarthy appears briefly as a man on the street frantically screaming about aliens (in a shot reminiscent of the final shot of the original) and Don Siegel appears as a cab driver. Grateful Dead guitarist Jerry Garcia also appears briefly, as does Robert Duvall.
The 1978 version was adapted by W.D. Richter and directed by Philip Kaufman, and, unlike many remakes, met with generally favorable critical response. Lacking the Cold War subtext of the original, Kaufman concentrated on a style of paranoia that was more reflective of the mistrust and malaise pervasive in post-Vietnam, post-Watergate America. Kaufman's film is set not in a small town but in San Francisco; in one scene, Sutherland's character calls Washington for help, only to find his calls are being intercepted and his name is known to the person on the other line before he gives it. The script could thus be thought to reflect growing anti-government fears that would later manifest themselves among conspiracy theorists. There are distinct similarities between the 1978 film and the tone of the "mythology" episodes of the popular 1990s television series The X-Files.
A 1993 version, called Body Snatchers, stars Terry Kinney, Meg Tilly and Gabrielle Anwar. It was adapted by Raymond Cistheri, Larry Cohen, Stuart Gordon, Dennis Paoli and Nicholas St. John, and was directed by Abel Ferrara. This time the story was set on a military base, and did not attempt to follow the plot of either the original or the 1978 version. In its structure it plays like a straightforward alien invasion thriller, and does not attempt to create the overriding paranoiac mood of the earlier films. It did not receive wide theatrical distribution and was for the most part critically panned.
As of 2003, rumors of yet another remake were circulating.
The original version has been selected for preservation in the United States National Film Registry.