A blanket of white covers Montreal inside and out in this understated, affecting Canadian drama. The schoolyard where Alice (Sophie Nélisse) and Simon (Émilien Néron) exchange their usual morning jabs is capped with snow, their classroom filled with bright winter light. Within the film’s first minutes, the brisk, clean-aired comfort of that light is cut by an incongruous moment of darkness, and the rest of writer/director Philippe Falardeau’s fourth feature charts the resulting wave of grief as it breaks across a school community. Alice and Simon’s class gets a new coat of paint and a new teacher—the monsieur of the title (Mohamed Fellag), a mysterious Algerian emigrant—as the school attempts to cope with an incident I’d rather not give away. Falardeau meshes Lazhar’s secrets and the hidden turbulence of the situation he has stepped into with a sensitivity that lifts the story out of refugee cliché. Nélisse, with her tough Courtney Love puss, and Néron’s portrayal of a boy’s well-defended torment, are both extraordinary, as is the film’s realization of the small, temporary world that surrounds them. Hitting upon that kind of specificity—of a moment and its emotion—makes for strong memories and a really great movie.