"The Box" is based on a famed short story by Richard Matheson called "Button, Button," adapted once before into an episode of "The Twilight Zone." Less than ten pages long but packing a devilishly compact wallop, it is easy to see how the source material might lend itself to the thirty-minute format of a television anthology series. In trying to stretch it to feature length, however, writer-director Richard Kelly has been forced to tack on a second and third act, conceived from his own imagination. This may not sound so bad coming from the ambitious filmmaker behind 2001's "Donnie Darko" and 2007's "Southland Tales," but that's where fans of his work would be gravely wrong.

The set-up is brilliant, and why wouldn't it be? It is this segment that author Richard Matheson so masterfully devised, albeit with Kelly's tweaks in setting and character occupation. Down-on-their-luck married couple Norma (Cameron Diaz) and Arthur Lewis (James Marsden) are happy enough with their peaceful life in Richmond, Virginia, circa 1976, but they aren't without their financial woes. With her as an English teacher who has just learned the discount on son Walter's (Sam Oz Stone) private school tuition is being taken away, and he as a technician at Langley Research Center who has just found out he has failed a critical part of the test required to become an astronaut, Norma and Walter are facing a long future living paycheck to paycheck. After receiving a mysterious box on their doorstep with a red button inside, Norma is paid a visit by Arlington Steward (Frank Langella), a personable, well-spoken fellow with the misfortune of only having little more than half of his face intact. He lays it out for her: push the button within twenty-four hours, and someone in the world whom neither Norma nor Arthur knows will die. In return, they will be provided a briefcase filled with one million dollars in cash, tax free. They cannot tell anyone else about this, and if they do not push the button, it will be collected and dropped off at another couple's home.

It is not giving anything away to reveal that the Lewis' do, indeed, push the button (there wouldn't be a movie otherwise), but it is interesting all the same to watch them grapple with the moral quandary. Norma and Arthur are genuinely good people, but the lure of economic freedom is something they cannot resist. It also, as it turns out, is their undoing. As they rightfully begin to fear for their own lives and are haunted by strange occurrences and casual acquaintances who seem to be in cahoots with the people Arlington works for, Norma and Arthur become trapped in a nightmare they can't escape from. "The Box," like "Button, Button," offers the same age-old message: be careful what you wish for. Beyond that, writer-director Richard Kelly sends his film—an amalgamation of the sci-fi, horror and paranoid thriller genres—off on a bunch of wild, convoluted tangents that don't add up and grow sillier by the minute. The ending, which will most certainly not be given away, can be easily guessed by the halfway point when it is foreshadowed by a virtual neon sign, but that doesn't mean it actually makes sense. By the time nosebleed epidemics, watery portals and out-there NASA experiments are added into the mix, the picture has walked off a ledge it never recovers from.

Sporting a disarming southern Virginia accent and some choice 1970s costumes and hairstyles, Cameron Diaz (2009's "My Sister's Keeper") fits splendidly for the second time this year into a cinematic world that isn't in the romantic comedy mold. While Diaz's Norma makes the wrong decision in pressing the button, the viewer can empathize with her by questioning what they would do in her situation. One of Richard Kelly's few original flourishes that do work, Norma walks with a limp, the result of a teenage incident that left four of her toes amputated. Living her life with that insecurity always in the back of her mind, she instantly feels an unspoken connection with the facially deformed Arlington Steward and allows herself to trust him. As Arlington, Frank Langella (2008's "Frost/Nixon") underacts appropriately—his face, created with CGI, does most of the expressing for him—and essays a non-violent villain who would be perfectly charming if he didn't have such a fiendish ulterior motive. Finally, the largely uneven, usually bland James Marsden (2007's "Enchanted") is just that as Arthur Lewis. Marsden isn't a bad actor, but he more often than not is upstaged by his co-stars. This surely happens here as he performs next to Diaz.

Try as it clearly does to approach Hitchcockian levels of suspense, "The Box" is a mixed bag not taut enough to build tension and too longwinded to keep the viewer actively engaged for almost two full hours. The first act is as good as it gets before director Richard Kelly wanders down multiple paths of semi-supernatural hogwash. He earns one solid startle involving a bell-ringing Santa and an unseen truck, and finds occasionally palpable emotions through his use of music and image—Eric Clapton's "Bellbottom Blues" is memorably incorporated in a scene where Arthur spots Norma dancing through a window at a rehearsal dinner. Otherwise, "The Box" is but a faded shadow of the superior short story. If these were Kelly's best ideas in expanding the material, perhaps it would have been wise to keep the ingenious tale on the written page.