The book jacket description says this is the story of the assassination of Reinhard Heydrich (The Hangman of Prague) and the two men who succeeded in that mission. I'm not convinced the person who wrote the description actually read the book. HHhH is more accurately described as a bit of a history of Heydrich, some speculation on the guys who executed him, mixed together with many musings of the author who wants to be writing history but doesn't really have enough facts to do so. It's not for lack of trying, it's just that so little is actually known about those two men and their commission that he doesn't have much to draw from.
The good: this book is full of interesting information on the life of Reinhard Heydrich, from early childhood through his succession to Hitler's "protector" of Prague. For Hitler, Heydrich represented the perfect Aryan, the blonde hair, blue eyes, slender nose and build. And Heydrich also had a mind toward evil, which apparently instigated much that went on within the concentration camps. The title of the book, HHhH, which in German stands for "Himmler's Hirn heisst Heydrich" translates to "Himmler's brain is Heydrich" and supports the idea of Heydrich's evilness.
The bad: very little of the book actually dealt with Operation Anthropoid and too much of the book dealt with the author/narrator, who vacillated from whining to bragging to fantasizing.