From 1975-1979, the Khmer Rouge, led by Pol Pot, instituted a series of murderous purges that took place at S21, a high school turned interrogation and torture center in Phnom Penh where 17,000 prisoners were "processed." Only three lived to tell about it. Vahn Nath, an artist, relates his story of survival by painting flattering portraits of the guards. Journals kept by guards and re-creations describe the painful techniques used on prisoners. Director Rithy Panh (himself an inmate at S21) takes an unvarnished look at the horrors perpetrated in the name of the state.