Rithy Panh's film S-21. The Khmer Rouge Killing Machine (2003) was the result of a three- year shooting period in the Khmer Rouge centre of torture where perpetrators and victims exchanged experiences and re-enacted scenes from the past under the gaze of the filmmaker's camera. Yet, a crucial testimony was missing in that puzzle: the voice of the prison's director, Kaing Guek Eav, comrade Duch. When the Extraor- dinary Chambers in the Courts of Cambodia (ECCC) were finally established in Phnom Penh to judge the master criminals of Democratic Kampuchea, the first to be indicted was this desk criminal. The film Duch, Master of the Forges of Hell (Panh, 2011) deploys a new confrontation - an agon, in the terminology of tragedy - between a former perpetrator and a former victim, seen through cinema language. The audiovisual document registers Duch's words and body as he develops his narrative, playing cunningly with contrition and deceit. The construction of this narrative and its deconstruction by Panh can be more fully understood by comparing some film scenes with other footage shot before, during and after the hearings. In sum, this 'chamber film' permits us to analyse two voices: that of the perpetrator, including his narrative and body language; and the invisible voice of the survivor that expresses itself through editing, sound effects, and montage.