How could the Nazis have committed the crimes they did?Why did they willingly – often enthusiastically – oversee mass murder?How did ordinary Germans tolerate the removal of Jewish people?And how do we ensure it never happens again?Bestselling author Laurence Rees combines history and the latest psychological research to help answer the most perplexing questions surrounding the Holocaust and the Nazi state. Through the lens of ‘twelve warnings’ – from talk about ‘them’ and ‘us’ to the escalation of racism – Rees delves into the darkness to explain how and why people were capable of such horrors. Using previously unpublished testimony from former Nazis and cutting-edge psychological discoveries,