The Rio de Janeiro slum known as Cidade de Deus might be a Martian landscape, so remote in spirit is it from the smooth beaches where the rich work on their tans and lines of seduction. In the inner city the activity is life-and-death, mostly death, and the ruthless men who run the place are boys, some not yet adolescents. Boys their age elsewhere play with plastic guns; these kids shoot real bullets, kill people, for the love or the hell of it. Bang, you’re dead. Ha ha. Luis Bunuel’s Los Olvidados portrayed similar young toughs in Mexico City a half-century earlier, using a mixture of realism and surrealism. Meirelles and Lund used a pinwheeling, hypertrophic style; no static camera could keep up with the hurtling pace at which these kids rushed to their doom. As sociology, it’s tragic; as cinema, a stupendous, joyous jolt.