In April 1975, after a war in which 600,000 people died and the US rained down half a million tonnes of bombs, Phnom Penh fell to a band of child soldiers in blackened rags who wanted a communist paradise on earth. For the middle class, collaborators, the educated, the travelled and city-dwellers, it was the end of the world. In four years of Khmer Rouge rule a quarter of the population perished.
Unsurprisingly, justice is an emotional issue in Cambodia, and over the years most people had little hope that there would ever be a reckoning for what happened. Against expectations, however, something is finally happening: under an agreement between the UN and the Cambodian government, the Extraordinary Chambers in the Courts of Cambodia (ECCC) this month began a process that aims to deal out justice to Khmer Rouge leaders.
A handful of senior regime figures will be in the dock, probably including Nuon Chea, the Khmer Rouge's "Brother Number Two", and Ieng Sary, the foreign minister who was the international face of the genocide. It is too late to try their leader, Pol Pot, who died in 1998.
The team of Cambodian and international judges gathered early this month at the dusty military base near Phnom Penh that is to be the seat of the ECCC, where they were due to go through an induction process before setting in motion the preparation of cases.
Unlike other tribunals for crimes of this magnitude, the Khmer Rouge trials will be held under local law, and under its deal with the UN the Cambodian government also won the right to appoint most of the judges. It knows, however, that outside participation is vital if the court is to reach international standards.
The UN is also determined to make this work. At a time when US pressure is threatening the future of the International Criminal Court and the new UN Human Rights Council, a successful trial would answer critics of international justice. It could also provide a model for such trials in future: other tribunals have been criticised for remoteness, but the Cambodian court is locally based and will be accessible to ordinary people. The court will lay on buses to encourage Cambodians to see justice done.
What is less clear is how Cambodians will deal with the emotional strain. A quarter of them are thought to suffer from severe post-traumatic stress disorder; revisiting those years is likely to be an ordeal. And though this is a country of 14 million people, it has only a handful of psychiatrists.