By any standards, this was an unusual choice for me. The story of the assassination in Prague of Reinhard Heydrich, architect of the Final Solution and one of the most terrifying figures in the Third Reich, is not the natural successor to Dorothy Dunnett’s Gemini. It is certainly not the kind of book I would pick out for myself. But it was persuasively and persistently recommended to me by someone whose opinion I respect a great deal and so I decided to give it a whirl. It was the right decision.