After the conventional period drama The Young Victoria, Jean-Marc Vallée returns to the more complex, decade-hopping M. O. of his breakthrough, C. R. A. Z. Y.. Using different versions of the title song as a through-line, Vallée flits between two stories, juxtaposing a mother (Vanessa Paradis) coping with a mentally challenged son in '60s Paris with a DJ (Kevin Parent) finding new love while his ex-wife (Hélène Florent) struggles to come to terms with the break-up. Both stories are engaging as are the filmmaking styles - shallow focus for the contemporary, a softer, gauzier feel for the '60s. Yet despite a plethora of strong scenes, how the two strands come together requires a leap of imagination many will find too far to make.