In the modern technological war, victims are distant and responsibility is fragmented. The scientists making the atomic bomb thought they were only providing a weapon: how it was used was the responsibility of society. The people who dropped the bomb were only obeying orders. The machinery of political decision-taking was so complex that no one among the politicians was unambiguously responsible. No one thought of themselves as causing the horrors of Hiroshima. One topic of the book is tribalism: about how, in Rwanda and in the former Yugoslavia, people who once lived together became trapped into mutual fear and hatred. Another topic is how, in Stalin's Russia, Mao's China and in Cambodia, systems of belief made atrocities possible. The analysis of Nazism looks at the emotionally powerful combination of tribalism and belief which enabled people to do things otherwise unimaginable. Drawing on accounts of participants, victims and observers, Jonathan Glover shows that different atrocities have common patterns which suggest weak points in our psychology: only by looking closely at the monsters inside us can we undertake the project of caging and taming them.