I recently read 'The Rise and Fall of the Third Reich' by William L. Shirer and am currently reading 'Hitler's Hangman: The Life of Heydrich' by Robert Gerwath. These books have piqued an interest in secret policing/intelligence work, and I'd like to learn more, not just about the history of the organizations involved but about their structures, methods, and effectiveness. I'm looking for books about anything from the Stasi to the CIA to Joseph Fouche, and I'd be happy to know what people in this sub would recommend.