SAN DIEGO — "Indecent Proposal" had moviegoers worldwide debating the 1993 movie's central question: Would you loan a loved one to someone else for a $1 million night of passion? "The Last Supper" in 1995 had James Marsden explained recently about "The Box," which opens November 6. "Someone you don't know will die. Would you push this button?"

It's a question posed by a mysterious man played by veteran actor Frank Langella, who presents a suburban couple with a box that will make them wealthy if they press its button — but will also kill someone somewhere in the world. Directed by "Donnie Darko" mastermind Richard Kelly, it features Diaz returning to the provocative moral dilemmas she explored in her early work.

"It's a simple idea, but at the same time, it's one of the most profound questions," Diaz said, noting that the box itself could serve as a metaphor for everything from road rage to workplace competition to eating red meat. "We're pushing buttons every day. There's always a repercussion to our actions. There's always a consequence to our actions, no matter how big or small it may seem. But every choice that we make throughout the day, somewhere, has an effect."

Over the past few years, Kelly has earned a reputation as the sci-fi Mike Judge — writing and directing a pair of ambitious, frequently brilliant films that were re-edited, delayed and unceremoniously released into theaters. Now, the same die-hard fans who revived those films on DVD are hoping "The Box" will finally establish him as more than a cult filmmaker, and with a powerful score by the Arcade Fire, this film could be something special.

"It's a very, very intense, emotional roller-coaster ride," Kelly explained, claiming that Diaz's performance is a particular strength of the film. "Cameron worked harder in this role than anyone; I've never seen an actor work harder than she did. ... In this role, she has a very specific Texas accent, and she has some physical disability issues with her character that she did very elegantly. ... Her character goes through a lot in this film, and I couldn't be more proud of her."

Those "physical disability issues" aren't glimpsed in the film's trailer, but suffice it to say that once people begin pressing each other's buttons — in both senses of the phrase — the movie takes some very dark turns.

"This film is about responsibility. What constitutes responsibility when it comes to someone else's life?" Kelly asked, posing what he hopes will become the most provocative question of the fall movie season. "It's going to send audiences out of the theater asking the question — particularly married couples, boyfriends and girlfriends and any kind of people in a relationship. What would we do if confronted with this opportunity?"

From the sexy Megan Fox in "Jennifer's Body" to the black-clad warriors of "Ninja Assassin," the MTV Movies team is delving into the hottest flicks of Fall 2009. Check back daily for exclusive clips, photos and interviews with the films' biggest stars.

Check out everything we've got on "The Box."

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