Filmmaker Richard Kelly's initial encounter with Richard Matheson's fiendish little short story "Button, Button" — about a cash-strapped couple offered a million dollars to push a button on a box that will instantly cause someone they don't know to drop dead — came not on the page, but on TV.

"As a bunch of attorneys have informed me, I am not allowed to exploit the name of a certain television program to help promote the movie," Kelly says with a chuckle from his production offices in Los Angeles. We, however, are free to state that Kelly first experienced Matheson's devilish little ditty as an episode of "The Twilight Zone" revival that aired in 1985.

When Kelly later read Matheson's six-page story, he was surprised to discover the show had taken considerable liberties with the source material (enough so that Matheson insisted his name be removed from the episode's credits).

"The story is pretty thin, but it has this absolutely brilliant conceit that was absurd and scary and kind of diabolical," Kelly, 34, says. "But it also cultivated so many ideas about greed and morality and a married couple's approach to the dilemma that this device brings into their lives. The story stuck with me for a long time."

And the dramatically different ending of the TV adaptation sparked an idea in Kelly's mind.

"I realized the story could serve as a wonderful first act of a feature film, where the button is pushed, and the couple realizes it has far greater consequences than they realized, and they're going to be put through a much more extended psychological endurance test of some kind. The question becomes: Can they redeem themselves?"

"The Box," which stars Cameron Diaz and James Marsden as the married couple and Frank Langella as their exceedingly odd (you have NO idea) visitor who makes the offer, is Kelly's third film after the bona fide cult classic "Donnie Darko" and "Southland Tales," which was so resoundingly booed at its Cannes premiere that Kelly re-edited and chopped out a half hour — and it still made practically no sense.

The early buzz on "The Box" was that this would be Kelly's grab at mainstream success, with a simple and accessible premise and an easily identifiable genre. But although the film's first half is exactly that — a thriller — its second half starts to veer away from anything resembling "simple." So many conceits and complex ideas spring from that innocuous-looking box, and woe to anyone who dares run out for popcorn when the plot kicks into overdrive.