Chile 1973. Two children, aged 11: the timid Gonzalo Infante comes from a well-to-do family living in the fashionable quarters; Pedro Machuca, a peasant's son, gets by in a shantytown. These two children, who have nothing in common, will meet at school thanks to an idealistic initiative by Father MacEnroe. His aim is to integrated children from underprivileged sections of the population into the posh Catholic school he is principal of in Santiago. He wants to teach respect and tolerance when the political and social climate is degenerating in the country.