It’s not hard to understand why Dheepan, by the French director Jacques Audiard (Rust and Bone), won the Palme d’Or at Cannes: It’s at once a drama, a polemic, and a work of sociology, moody and exotic, but just familiar and relevant enough. The title character is a Hindu Tamil insurgent from Sri Lanka (where the Buddhist Sinhalese dominate) who escapes to Paris after assembling a family of strangers — a churlish woman and an anxious child — hoping they’ll make it easier for him to emigrate. He finds a job as a caretaker at a building complex in the suburbs, and he works with commitment. But drugs and thugs swirl about this milieu, and the erstwhile warrior gets drawn in to protect himself and his family. Parts of Dheepan explore the enormous challenge of assimilation, and Audiard concludes that it requires diligence and personal effort. Hope alternates with despair, and he eschews sentimentality or easy solutions. His climax is brutal and seems to ask whether the tumultuous “third world” is really much worse than our own. And then, there’s a dreamy coda — or is it really a dream? Filmed long ago, of course, this final minute becomes suddenly ironic in the age of Brexit.