Belgium lost the last of its colonial empire -- one of the most brutally repressive of modern times -- three decades ago. But as brothers Luc and Jean-Pierre Dardenne's La promesse demonstrates, a more insidious colonialism persists. Like the late Rainer Werner Fassbinder, the Dardennes recognize that the roots of human exploitation and tyranny lie not in governments or institutions, but in the basic unit of the family and in individual love relationships. Unlike Fassbinder's baroque melodramas, however, La promesse unreels its uncompromising and compassionate vision with stark simplicity and clarity. Brilliantly acted by its cast of unknowns, the film enacts the historical tragedies of greed, inhumanity, and indifference in the uncomprehending faces of its characters.

It takes place in the filmmakers' own hometown of Seraing, a bleak, economically blighted suburb of Liège with a desolate pallor of anomie not even Michelangelo Antonioni could love. The biggest industry appears to be hustling illegal immigrants, and that's the trade that pudgy unemployed factory worker Roger (owlish Olivier Gourmet) plies with hamfisted ruthlessness. He lodges refugees from Eastern Europe, Africa, and the Middle East in his freezing cinderblock building at extortionate rents, hires them out to construction crews, shakes them down for their government handouts, and thinks nothing of turning them in to the authorities to cover his substantial butt.

Helping in the family business and learning its fine points is Roger's son Igor (Jérémie Renier, who looks like an ethereal Martha Plimpton). No angel despite his looks -- he's first seen relieving an old lady of her purse at the garage where he works halfheartedly as an apprentice -- Igor is unmoved until Hamidou (Rasmané Ouedraogo), a worker from Burkina Faso, falls, critically injuring himself. Roger ignores Igor's pleas to take the man to the hospital, since that would uncover his illegal operation. Bleeding to death, Hamidou begs Igor to take care of his wife, Assita (Assita Ouedraogo), and their child. In a scene of extraordinary power, Igor mutely discovers a conscience and agrees.

Of course Igor is torn between his loyalty to his father -- who though abusive clings to the boy with pathetic need -- and his promise to Hamidou (there's also his growing fascination, sexual and otherwise, with the exotic Assita). This conflict might have been rote and mawkish if not for the filmmakers' rigorous dramatic restraint and cinematic style. Using very little dialogue but relying instead on close-ups, pointed compositions, and ironic editing, they trace the slow initiation of a stunted young life into the world of compassion and responsibility. Although offering no happy endings or solutions -- the final shot is a masterpiece of ambiguity reminiscent of The 400 Blows -- the film suggests that even the most benighted human beings have the potential to be redeemed. At the Coolidge Corner.