Claire Denis's first film, Chocolat (1988), was an anti-colonialist tale set in French West Africa, but with enough attention paid to the white colonialists, and to the jungle scenery, to attract an American arthouse audience. Since, Denis's films have been as unwanted here as they've been uniformly excellent: hardboiled sagas of France's underweb of Third World illegals and marginals trying to make a go of it in their mother-of-an-adopted country. S'en fout la mort (1989) was about African cockpit workers; J'ai pas sommeil (1994) was a politically incorrect story of an African-in-Paris serial killer.

In her tender, mesmerising new Nenette et Boni, Denis switches locales, to Marseilles, but her sibling protagonists are, again, among society's seeming losers. Boni (Grégoire Colin) is an 18-year-old school dropout who runs a pizza wagon, sells contraband fishing rods from Taiwan, and has vivid masturbatory dreams of fornicating with the baker's wife (Valeria Bruni-Tedeschi); Nenette (Alice Houri) is his sour, darkly beautiful, deeply pregnant 15-year-old sister. They've lived apart, and estranged, since their parents split. He's inherited a slum apartment from his recently deceased mother. She's stayed on with her weak-spirited father (Jacques Nolot), though she runs away when she discovers herself with an unwanted child. As Nenette et Boni proceeds, the reticent brother and sister slowly edge together, though nothing is said. This is a quiet, quiet movie of moods, glances, penetrating looks. Ultimately, there's a lovely, unexpected sacrament, and Claire Denis's most (tentatively) benign ending. At the Kendall Square.