The movie was born of a fateful accident, director Rithy Panh told me over coffee in Phnom Penh, Cambodia, last year. That film is S21: The Khmer Rouge Killing Machine, Panh's harrowing documentary about the ultra-Maoist movement's main detention center, a Phnom Penh high school that was transformed into an interrogation, torture, and death camp, code-named S-21. Now making its way across the United States, S21sheds a harsh light on some of the issues raised on a smaller scale at Abu Ghraib -- about the documentation of prisoners' mistreatment, and on environments where the dehumanization of detainees has become routine.