Most people would probably point you to the George Smiley books, but I'd say his last book - Agent Running in the Field - is as good a place to start as anywhere. He forged his reputation as a chronicler of the Cold War, but since it effectively ended in 1989 he's produced some very interesting work looking at the fragmented nature of the New World Order. In the early books there was a clear demarcation: the West vs the Eastern Bloc (though he always allowed for moral ambiguity). Post 1989, it's become more difficult to identify the 'bad guys', and he's had fun with that. In the last book, he explores what loyalty means.Can anyone suggest a good starting point for his work or the best of the best?