Maggie Cheung makes a pretty unconvincing junkie rock chick in her second collaboration with ex-husband Olivier Assayas - they famously finalised their divorce on the set of the film. She plays the wife of a faded 1980s rocker whom she inadvertently helps out of his tortured existence by buying him some dodgy heroin, then disappearing to shoot up herself while he dies in their cheap hotel room. Back in Vancouver, the grandparents hold on to their son, and Emily must clean up her act if she ever wants to see him again.

Cheung isn't helped by Assayas' uncomprehendingly gormless idea of rock'n'roll grunginess, in which frizzy hair, paint-splattered T-shirts and much arguing about "genius" figure strongly. But inside the carapace of music world cliche is a rather sad and moving little story about a woman trying to get her child back, and it's in the scenes where no music or drugs are evident that Cheung excels, offering a tenderness and sensitivity that make you realise how gifted an actress she is. Nick Nolte - looking alarmingly like his legendary mugshot - is also a strong, affecting presence as the protective grandpappy. Béatrice Dalle, though, is less well served in an pal-from-the-old-days role that doesn't have much to do with anything, seemingly existing only to ballast the Parisian section of Assayas' continent-hopping script.