Chronicles what has happened in Rwanda and neighboring states since 1994, when the Rwandan government called on everyone in the Hutu majority to murder everyone in the Tutsi minority. Though the killing was low-tech--largely by machete--it was carried out at shocking speed: some 800,000 people were exterminated in a hundred days. A Tutsi pastor, in a letter to his church president, a Hutu, used the chilling phrase that gives Philip Gourevitch his title.