Suggest me a non fiction book (about Cold War or previous period) that deals with methods of espionage and investigation of agencies like CIA, KGB, etc.

I'd like to read more on real life espionage, missions and all the inside drama of political intelligence agencies. Could be about WW2 or Cold War. Don't want anything about post-2000. Can be about anything on any country, but one final caveat: I don't do well with biographies so non-fiction first person or a lifespan of a single agent/mastermind isn't really what I'm looking for.

Ps: never read anything of the sort so throw all your suggestions even if they're too obvious to you.

Thanks!