A prickly woman’s survival depends on her ability to soften her edges in this riveting drama by Olivier Assayas, for which Maggie Cheung won the Best Actress award at the Cannes Film Festival in 2004. Assayas began his career by making incisive and unsentimental character studies. His technique became freer in his first collaboration with Hong Kong star Cheung, “Irma Vep,” and his canvas became wider with the kinky multicultural piece “Demonlover.”

by Betsy Sherman

In “Clean” (which opens at the Kendall Square Cinema tomorrow) Assayas goes deep and wide as he focuses on a many-faceted character who maneuvers skillfully in the often devious world of the music business, but finds it hard to operate with sincerity in the so-called real world.

Cheung plays Emily, a former VJ on French TV whose more recent claim to fame was as the abrasive girlfriend of a Canadian rock star. Shaken by her boyfriend’s death from a heroin overdose and her own struggle with addiction, Emily clings to the hope that she can someday take care of her son, who lives with her boyfriend’s parents in Vancouver (Nick Nolte plays the grandfather). The drama plays out in Canada, London, and Paris . The versatile Cheung has given many fine performances, but in “Clean” she is a towering presence, exploring Emily’s painful passage into maturity, from self-centered belligerence to a more humble, open-minded view of her place in the universe.