Heinrich Himmler was an unremarkable looking man. Yet he was Hitler's top enforcer, in charge of the Gestapo, the SS, and the so-called Final Solution. We can only wonder, as biographer Peter Longerich asks, how could such a banal personality attain such a historically unique position of power? How could the son of a prosperous Bavarian Catholic public servant become the organizer of a system of mass murder spanning the whole of Europe?

In the first comprehensive biography of this murderous enigma, Longerich answers those questions with a superb account of Himmler's inner self and outward...