The World's End
by Simon Pegg and Edgar Wright
(Focus Features)

The Invasion of the Body Snatchers
By Jack Finney
(Simon & Schuster)

     There have been at least four official adaptations of Jack Finney's paranoid science fiction horror classic The Invasion of the Body Snatchers (the third was just titled Body Snatchers and the fourth just The Invasion; the next will probably be Of), but they all failed to depict the author's original ending. The World's End isn't strictly speaking an adaptation of Finney's novel, though it has many similarities, including an approximation of its ending. I can't say for certain that writers Simon Pegg and Edgar Wright have actually read Finney's book, but after seeing their film I'd be surprised to learn they hadn't.
     There will be SPOILERS, so if you haven't seen the film and/or read the book in question, look away now. Suffice to say, I throughly enjoyed The World's End as I did Shaun of the Dead (an obvious tribute to George Romero's Dead films) and Hot Fuzz (which paid homage to another favorite of mine, The Wicker Man, even including the star of that film in a prominent role).

     Everyone out who's getting out? Good.

     Invasion of the Body Snatchers is, as most filmgoers are aware (even if they haven't seen any of the film versions) about pods from outer space that drift to Earth, duplicate perfectly and replace people down to their memories and scars with one difference: they have no emotions. The usual tack of the films is to suggest that the pods are able to take us over because we've pretty much taken ourselves down that path already, and it was an effective and satisfying theme in the first two films at least. In both, near the end, the male protagonist discovers that the female protagonist, his girlfriend, has succumbed to the pods (if you fall asleep, they can take you over). It was not the ending that Finney wrote, however. Either because he was more optimistic about humanity than the filmmakers or because he lacked the conviction to put such a downbeat ending on the novel, he ends it before the female lead is replaced, with the pods realizing that they cannot conquer man's indomitable spirit, and give up, blasting off into space en masse. Those pods that have already taken over and replaced people remain, but live their lives the way those people would have, more or less, and the surviving human let them be.
     That is almost exactly the ending of The World's End.
     The World's End is about five old school buddies from a small town who return there for an epic 10-pub crawl, during which they discover almost everyone in the town has been replaced by some sort of artificial creature from outer space. They're closer to robots than pods, though they deny they are robots, and seem to have the essence of the people in them (though whether it's a copy of that essence or just a transfer isn't really established).
     At the end, the remaining humans persuade the aliens that although they think they're doing this for our own good, it's not working; they've had to replace virtually everyone. So the aliens depart, leaving the replicants to live out their lives as well as they can ... although the alien's departure has also removed almost all of our technology (apparently the aliens were responsible for it) and killed a lot of people.

     That doing it for our own good bit is reminiscent of another film/book, too: The Monitors. In that, aliens do take over the world for our benefit, and give up when they realize how self-destructive we are and that their presence is actually making it worse. In the film version, the aliens leave; in the book, they allow the humans to hire them to run things so it doesn't seem like an invasion/takeover.