Santiago, Chile, 1973: Pedro Machuca is a poor boy of tribal descent, brought into an upper class private school during Chile’s brief socialist era. Gonzalo, the well-to-do boy seated a row ahead, befriends Pedro against the bullying will of his classmates. In so doing, he discovers a raw, thrilling but wildly complicated world outside his own previously sheltered homelife. Pedro’s fierce, attractive young neighbor Silvana by turns mocks Gonzalo’s pampered background, only to fondly lead both boys in a number of kissing games. All around them, Chile drifts towards civil war. At school, their humane headmaster Father McEnroe comes under a hysteria-driven attack by parents for his charity toward poor students. Little Gonzalo must also contend with more intimate kinds of upheaval. His sexy, melancholy mother is having a love affair with a wealthy older man. His father is sweet but ineffectual, and lacks the fire to fight for his marriage. He therefore escapes into his friendship with Pedro. Pedro gets a look at the intense dysfunctions in Gonzalo’s life, and Gonzalo in turn is immersed in Pedro’s world of extreme poverty. The two boys share a love of comic books devoted to the Lone Ranger. With Silvana’s encouragement they also take part in protest marches--selling cigarettes and flags to demonstrators on the right as well as the left, but chanting with committed vigor when marching with the left. The already enormous rift between Gonzalo’s comfortable household and Pedro’s hard-scrabble life a few miles away in an illegal shantytown ultimately becomes impossible to bridge, once the bloody military coup of September 11, 1973 erupts. All three children suddenly face moral tests far beyond their young capacities.