In 1926, at the age of twenty, a trainee dentist called Bruno Langbehn joined the Nazi party. Growing up in a Germany that was impoverished and humiliated by the defeat of the First World War, and surrounded by a fiercely military environment, Bruno was one of the first young men to sign up. And as the party rose to power, he was there every step of the way. Eventually his loyalty was rewarded with a high-ranking position in Hitler's dreaded SS, the elite security service charged with sending Germany's "racially impure" to the death camps. For fifty years after the end of the Second World War, his family kept this horrifying secret until his British grandson, Martin Davidson, uncovered the truth. Drawing on an astonishing cache of personal documents, Davidson retraces Bruno's journey from disillusioned adolescent to SS Officer to mysterious grandfather. In this extraordinary account he tries to understand how Langbehn and millions of others like him were seduced by Hitler's regime, and attempts to come to terms with this devastating revelation.