Jack Finney's book, The Body Snatchers (1955), was first adapted into a film back in 1956, where Finney's tale of alien spores taking duplicating and killing the human population, became an allegory for the Soviet "Red Menace" of the Cold War era...
Such political allegory was never the novel or original film's intent, but The Body Snatchers has since become a celebrated science fiction idea that always adjusts to its times. Director Philip Kaufman's 1978 remake of the '56 original is perhaps the more popular version...
It starred Donald Sutherland as San Francisco health inspector Matthew Bennell -- who realizes the world's population are being replaced in their sleep by clones grown from "alien pods". The resulting "Pod People" are identical to the original humans, but lack emotions -- so Matthew joins up with others to try and halt this stealth-like alien invasion, before the world is taken over.
The 1978 remake was considered an allegory for political mistrust in a post-Watergate, post-Vietnam America. This is most obvious when Sutherland's character calls Washington and finds the voice on the other end knows his name and has been intercepting his calls. Many people also consider the film a satire of the so-called "Me Decade", with a self-hero guru (played by Star Trek's Leonard Nimoy) dismissing the notion of an alien invasion, but later endorses it.
Most famously, the 1978 remake disposed of the original's happy ending (where the FBI were alerted to the situation and, presumably, took measures to stop the invasion). In the 1978 version, a classic twist ending is introduced. Interestingly, when the 1956 original was re-released in 1979, its happy ending was cut -- meaning both films now share a tragic finale.
Jack Finney's celebrated novel has been remade twice since 1978, too. In 1993, Abel Ferrara directed Body Snatchers, which received mixed reviews at the time, but is generally considered a worthwhile venture now.
More recently, The Invasion adapted the Body Snatchers idea again, and attracted the talents of Nicole Kidman and Daniel Craig. German director Oliver Hirschbiegel made his Hollywood debut with the film, after wowing critics with his WWII foreign-language film Downfall. The 2007 remake hoped to provide a post-9/11 allegory -- with terrorist sleeper cells obvious parallels for the "Pod People" walking amongst us.
The Invasion was a box office disaster in the US (and now the UK). As of 3 October 2007, it has taken just $20 million, but cost the studio $65 million to make! Some people claim Hirschbiegel's original cut just wasn't what the studio expected, so they had the Wachowski Brothers (The Matrix) write additional scenes and lengthy re-shoots were done by James McTeige (V For Vendetta), mainly adding action sequences.
Whatever the reasons for the latest remake's failure, the Body Snatchers idea remains a potent one, with its influence stretching across dozens of films and TV series ideas (like The Invaders). I'm sure the Pod People will return to cinemas another day, in a different political climate, with more success...
Trivia
1. The 1978 remake featured cameos from Kevin McCarthy and Don Siegel, actors who starred in the 1956 original.
2. Director Philip Kaufman cameos as a man rapping on the glass of a phone booth being used by Donald Sutherland.
3. Donald Sutherland insisted on performing his own stunts for the finale. A fireball erupting from a factory missed Sutherland, but seriously burned an extra in the explosion.