Oscillating from dynastic period epic in the stately ‘Les Destinées Sentimentales’ (2000) to wireless global dystopia in the self-immolating ‘Demonlover’ (2002), Olivier Assayas narrows his scope to a muted, wintry study of the needle and the damage done. In ‘Clean’, former VJ Emily Wang (Assayas’ ex-wife, Maggie Cheung) arrives in bleak Hamilton, Ontario, where her past-it singer-songwriter husband has a gig; after an argument, he dies of an overdose and she’s jailed for possession. Upon her release, Emily faces a bewildering mountain of challenges: stay away from smack, repair her Courtney Love-like reputation, place her prison-recorded demo into the right hands and, above all, restore her relationship with her young son, Jay (James Dennis), now in British Columbia with his paternal grandparents.‘Clean’ moves restlessly from Canada to Paris to London, tracking the peripatetic Emily’s encounters with a rare supportive pal (Béatrice Dalle) and an executive ex-lover (Jeanne Balibar), her waspish smile curdled with schadenfreude. The film’s path can appear as shapeless and desultory as Emily’s, and creates ripples of perhaps unintentional ambivalence: maybe little Jay would be better off if his flaky mum kept a respectful distance, and maybe Emily should forge a different comeback trail than the sub-Mazzy Star heroin dirges we hear in ‘Clean’. (Maggie sings!) The film locates its heart muscle, however, in its performances: Cheung won the Best Actress prize at Cannes in 2004, and Nick Nolte excels as Jay’s gentle granddad, silently ravaged with grief but, when it comes to his scattershot daughter-in-law, heroically keeping a firm, tender grip on the benefit of the doubt.