Alain Resnais is deservedly classed among the masters of world cinema, but “mastery” might be the wrong term to describe his method: Almost 50 years after Last Year at Marienbad, Resnais remains dedicated to experimentation, imagination and games of chance. Wild Grass, based on the novel L’Incident by Christian Gailly and titled after those stubborn weeds that erupt from cracks in the pavement, is an ode to uncontrolled impulse and the possibilities—effervescent or ominous, sublime or absurd—that arise from accident. The triggering incident is fairly ordinary: A woman goes out shopping for shoes and has her purse snatched; a man goes out to buy a watch battery and stumbles upon the woman’s red wallet. Out of these chinks in everyday routine grow a tangle of unruly emotions, as the man, Georges (André Dussollier), develops an inexplicable obsession with the woman, Marguerite (Sabine Azéma), a dentist and amateur aviatrix. Is Georges a melancholy romantic, an aging husband in the throes of some ongoing midlife crisis or a dangerous psychotic? Is Marguerite, with her staring eyes and blaze of scarlet hair, an endearing eccentric or has she entirely taken leave of her senses? Is Wild Grass a thriller, a screwball comedy, a love story? With false starts and false endings, sudden shifts of palette and a mood-swinging score, Resnais plays it as all three, and as something else entirely. As the weirdly omniscient narrator reminds us, “After the cinema, nothing surprises you. Anything can happen.”