In 1971, on a routine outing through the Cambodian countryside, the young French ethnologist François Bizot is captured by the murderous Communist guerrilas known as the Khmer Rouge. Accused of being an agent of "American imperialism", he is imprisoned.
His captor, Douch, later responsible for tens of thousands of deaths, interrogates him at length. The invisible high command tortuously ponders his fate, exploring his every utterance for counter-revolutionary nuance; after three months in chains he is freed.
Four years later, after a long fratricidal conflict, the Khmer Rouge enter Phnom Penh. With Southeast Asia torn apart by the Vietnam War and the Communist guerillas consumed by hatred of all things Western, Bizot stumbles into the unenviable position of official intermediary between the ruthless conqueror and the terrified refugees huddled behind the gate of the French embassy.
Forced to turn away asylum seekers, search for provisions in the ghostly capital, and organise a convoy through hundreds of kilometres of scorched countryside, Bizot is the only barrier between a genocidal army and thousands of desperate people.