In Cambodia, between 1975 and 1979, nearly two million people died at the hands of the Khmer Rouge. As head of the Khmer Rouge secret police, Comrade Duch was responsible for the murder of more than 20,000 people considered enemies of the revolution. Twenty years later, not one member of the Khmer Rouge had been held accountable for what happened. Like so many others, Comrade Duch had disappeared. Over a decade of working in Cambodia, photographer Nic Dunlop became obsessed with the idea of finding Duch. As the commandant of "S-21" prison, Duch could shed light on a secret and brutal world that had been sealed off to outsiders. Then, by chance, he came face to face with him. The Lost Executioner describes a personal journey to the heart of the Khmer Rouge. It is an attempt to find out what actually happened in Pol Pot's Cambodia and why; to understand how a seemingly peaceful nation could give birth to one of the most bloodthirsty revolutions in modern history.