In 1975-79, almost two million Cambodians lost their lives to murder and famine when the Khmer Rouge forced the urban population into the countryside to fulfill their ideal of an agrarian utopia.

The notorious detention center code-named 'S21' was the schoolhouse-turned prison where 17,000 men, women and children were tortured and killed, their "crimes" meticulously documented to justify their execution.

In this astonishing historical document, survivor Vann Nath confronts his captors, some of whom were as young as 12 years old when they committed their atrocities.