Compartmentalization refers to a process by which groups of people are put apart from others. In these compartments violent acts could be committed with complete impunity. Although many genocidal periods are discussed, this book is actually about the Holocaust and what the author calls ‘compartmentalization of the personality’. How can it be explained that Nazis felt no regret or guilt? What are the personality traits of these mass murderers? What are their personal motives? According to the author these criminals cannot be termed ‘ordinary people’ who were brought to killings by the situation they were in or pressure exerted on them. Individual choice and self-selection play a role.