Starring Matí­as Quer, Ariel Mateluna, Manuela Martelli, and Aline Kí¼ppenheim. In Spanish with English subtitles. Rating unavailable.

For radicals of my generation, the CIA--assisted coup that brought down the democratically elected Marxist government of Salvador Allende in September 1973 was the most traumatic event of our political lives. For once a bloodless revolution appeared to be working, and then it got squashed. What's more, while Gen. Augusto Pinochet's 3,000-plus victims might seem a small number by the standards of 20th-century mass murder, most of us knew some of the slaughtered, so the massacre seemed very, very personal.

The Chilean catastrophe has been fairly well served by the cinema. Patricio Guzmán's epic documentary The Battle of Chile set new standards for engaged nonfiction filmmaking, while Costa-Gavras's Missing still stands as one of the most scathing critiques of Washington's brutally controlling policies in Latin America.

Even these august forerunners, however, fail to match the emotional power of Machuca, director Andrés Wood's semiautobiographical account of the social divide that led to his country's current abyss. Quite simply, it is a masterpiece of historical filmmaking.

When a number of underprivileged children are brought into a posh private school by a progressive priest, 11-year-old Gonzalo Infante (Matí­as Quer) is intrigued. Although imbued with the same prejudices as his well-heeled classmates, Gonzalo reaches out, first to Pedro Machuca (Ariel Mateluna), and then to his precociously seductive cousin Silvana (Manuela Martelli), at least in part to combat the loneliness engendered by an unfaithful mother and a physically absent father.

Gonzalo lives in one of the nicer suburbs of Santiago; Pedro and Silvana inhabit a squalid shantytown where the possibility of indoor plumbing seems as remote as interstellar travel. From the very beginning, this friendship straddles the fault lines of class. Gonzalo's future is filled with possibilities; his newfound friends seem fated to experience more of their current existence unless President Allende can change Chile to the point where they might escape the cycle of poverty.

As a director, Wood is equally good at crowd scenes and intimate tíªte-í -tíªtes. The political marches fairly explode with joy and anger, alternately representing the hateful defence of oligarchy and the ecstatic arrival of genuine democracy. As for the coup itself, that is represented by the flight of two jets over the city. Anyone who's been touched by Chile's tragedy will know exactly where they're going.

Although Machuca is to some extent structurally beholden to Louis Malle's Au Revoir les Enfants, it's still a one-of-a-kind original. This is the most heartfelt movie of the year.