NEW YORK  _ "Clean" is the film that showed the world Maggie Cheung is more than just a strikingly beautiful face.

Hong Kong actress Maggie Cheung attends the premiere of her film "Clean" in Hong Kong November 29, 2004. Cheung was awarded the Best Actress title for her role in the film "Clean" by French director Olivier Assayas at the 57th Cannes Film Festival in 2004. [Reuters]

In an iconoclastic performance from one of the biggest stars of Asian cinema _ one that earned her the best-actress award in 2004 on the biggest international stage, the Cannes Film Festival _ Cheung plays a volatile, junkie rock star who must learn to become a responsible parent on her own after her volatile, junkie rock star husband dies of a heroin overdose.

The actress best known for her work in lush, elaborately costumed period films and high-profile cosmetics campaigns chain-smokes and curses her way toward redemption in three different languages (English, French and Chinese) and across various cities in Canada and Europe. She even goes to prison for drug possession and gets to tremble and sob as she suffers from withdrawal.

It's a wholly unexpected role _ one crafted for her specifically by her ex-husband, writer-director Olivier Assayas; the two signed their divorce papers on the set _ and the portrayal can be disarming. But it's also hard to believe that now she truly wants to raise her young son, Jay (James Dennis), who's been living in Vancouver with her disapproving in-laws (Nick Nolte and Martha Henry).

Cheung's Emily Wang says the words but only vaguely seems to mean them. She kinda tries to hold a job (as a waitress at her uncle's Chinese restaurant in Paris, at a department store that sells clothing she wouldn't deign to wear) but would rather pursue her fledgling attempt at a musical comeback. Even that goal is something she doesn't seem to strive for with complete conviction.

This is where Assayas' stripped-down, fly-on-the-wall approach tends to backfire on him. It can be quite effective in its intimacy, and it's refreshing that he doesn't play up the melodrama in scenes that already have sufficiently innate emotion.

Emily reunites with her son for the first time in years in a London hotel lobby _ a son who's never known her and believes she killed his father, since the heroin she scored was the stuff he OD'd on _ and all they do is look at each other and hesitantly hug. Moments like that feel real.

(Nolte, as the father-in-law who secretly brings Jay to Emily and gives her a chance to prove she can be a capable mother, recreates his familiar, craggy persona, only he seems to have softened and sweetened a bit with age.)

Much of the time, though, Emily seems to stagger through her own existence: crashing at various friends' apartments, using the little money she has to buy methadone, still looking fashionably distressed. Even the single she finally records is listless, though ostensibly it's intended as something deep and moving.

Maybe that's real, too. But it doesn't make for two hours of compelling cinema.

"Clean," a Palm Pictures release, runs 110 minutes. Two and a half stars out of four.