It explores the harrowing origins of the Khmer Rouge’s notorious security apparatus from 1971 to 1975. Led by Kaing Guek Eav, alias Duch, this “experimental school in brutality” trained operatives in torture and killing techniques, laying the groundwork for the infamous S-21 prison. The documentary delves into the site’s geography, the grim conditions endured by prisoners, and the brutal methods employed. It features firsthand accounts from two survivors: Mr. Sar Oun, who lost family members there, and Mr. Chan Voeun, a former guard. Insights are also provided by Mr. Nop Oun, now a local deputy head in Amleang commune.