Hitler's Hangman - the Life of Heydrich by Robert Gerwarth is the latest autobiography of Reinhard Heydrich.
It begins with the assassination of Heydrich in Prague on 27 May 1942 and then goes back to trace Heydrich's life from his childhood in Halle an der Saale to his career in the navy (cut short by a dishonourable discharge as a result of his womanizing) and then his rise in the party, closing the circle with his death a few days after the assassination and the aftermath.
Despite his reputation as a dyed in the wool-Nazi, Heydrich was not very interested in politics as a young man and he was not one of the veterans of the party. His wife, Lina, was a rabid anti-Semite and already a member of the party when they got married. She suggested looking for a job with the SS.
So it was more the thought of a secure job and the chance to earn military honours even after having been dismissed from the Navy that drew Heydrich to the Nazis. But once he had joined, he turned into one of the most feared and powerful men of Nazi Germany and he really believed in what he was doing. Which I think is a story found in the biographies of many party members, but still a fascinating one. It's easy to imagine yourself in his position - a young man with the chance to earn money and fame and power.
He was given the chance to almost single-handedly build the SD, after convincing Himmler that he knew what he was talking about with knowledge gleaned from spy novels - absurdities like that are also not uncommon in the history of Nazi Germany, especially when Himmler is involved.
The author dug up a lot of documents about Heydrich's private life and uses them to explore his character and motivations. A lot has been written about Heydrich as a ruthless, power-hungry man, a monster, but he wasn't born that way and it's interesting to see how he becamse Hitler's hangman (a moniker given by Thomas Mann when commenting on Heydrich's death). It doesn't hurt that the book is written in a very enganging style that makes it easy to read while being well-researched (the bibliography is massive. taking up almost 40 of the 478 pages).
I would have liked to read more about his wife. She outlived her husband by over fourty years and she never once expressed remorse or just second thoughts about what he had done. She always defended his actions, even though she claimed that she knew nothing about them at the time. I'm interested in the psychology of women like her or Winifred Wagner, who continued to adore Adolf Hitler until her death as well. There must be a lot of mental acrobatics involved in maintaining that position for decades. But that is worth a book of it sown.