Nancy (Maria Bello) wants to die. Louis (Jason Patric), an S&M creep she met on the Internet, wants to be of service. Albert (Rufus Sewell), Nancy's worm husband, can't figure out what to make of this movie. No, wait — that's us.

"Downloading Nancy," a film about self-mutilation, sexual sadism and dismal fluorescent lighting, features a world-class performance by Bello and an intriguingly spare one by Patric. But the story is so irritatingly jumbled that even the squalid enticements of voyeurism — the wretched BDSM games involving mousetraps, cigarette burns and jagged glass — are insufficient compensation for the movie's narrative confusion.

Nancy has been married to Albert, a heavily-repressed neat freak, for 15 years, and she's miserable. Because of the violent sexual abuse she suffered as a child, the closest she can come to pleasure is slashing her arms and legs with razors. A sympathetic shrink (Amy Brenneman) tries to help, but Nancy has had it: She can only experience love as a variant of pain and she just wants to end it all.

Bello's mastery of this character — her crippling timidity, fiery mood swings and hopeless self-loathing — is a prodigious thing to witness. And as Louis — who in a more commercially alert picture might have been a standard nightmare — Patric exerts an impressive restraint. We know Louis is a twisted guy — the walls of his apartment are lined with videotapes of his past sadomasochistic exploits. ("You'll be a whole shelf," he promises Nancy.) But there's more to the character — we learn in a fleeting comment that he has two kids he'll never be allowed to see again — and we get glimpses of his own pain flickering across Patric's stubbly face and seeping into his deep, mournful voice.

The movie is nonlinear in a pointless way, flashing forward and then back again and again, and it's often hard to be certain where we are in the narrative. Still, the picture has some superbly strange scenes, the eeriest of which takes place after Nancy has left Albert to surrender herself to her new e-mail friend Louis in Baltimore. (How far away that might be is never made clear; in any case, the whole movie was shot in Canada.) Louis comes to the couple's now half-empty home posing as a computer technician. Albert lets him in, but as it slowly dawns on him that this is actually the man who has taken possession of Nancy for some sick purpose, their desultory banter builds into heated male verbal wrangling and finally erupts into a vicious physical attack. Here, the first-time screenwriters, Pamela Cuming and Lee Ross (working from a "true story"), show an imaginative dramatic knack. Some praise may also be due to the Swedish director, Johan Renck, another first-timer, for rising above his background in TV commercials and music videos (Madonna, Beyoncé). Apart from an occasional stuttery editing tic, he resists trite artiness and maintains the film's bleak mood with grim determination.

Unfortunately, "grim" is not a word that lends itself to zesty poster blurbs. The movie is lit like an operating room (you'd never guess the great Christopher Doyle had anything to do with shooting it), and the several scenes of sexual assault and degradation lend it nothing in the way of uplift. That the characters of Nancy and Louis do have a compelling humanity is a tribute to the talents of Bello and Patric. But the part of Albert is bafflingly misconceived. Sewell has been directed to give one of the most bizarre performances of his career — his character is an inscrutable knot of emotional atrophy and oblique seething, and we wonder what his problem is. (He seems to be tormented by things outside the story.) Then we wish he'd go deal with it in some other movie — a picture that, like this one perhaps, not a lot of people would probably want to see.

Check out everything we've got on "Downloading Nancy."

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