A fascinating study in logic, reason and strategy. The difference between this and other approaches on this topic, is these are the reasonings of those who put their lives on the line based on the conclusions drawn. The application of these principles have real world potential even for us non-cloak and dagger types.
Disclaimer: If you are put off by a staccato style of writing and delivery, then find an easier listen. But if content trumps style, jump into the thoughts of a spy and prepare to learn.