Mixa, I think The Mission Song is the only Le Carre novel (other than the non-thriller love story he wrote back in the 60s) I haven't read. It doesn't have a great reputation. If you don't like it, don't let it be your only impression of LeCarre. I might even suggest skipping it and borrow The Spy Who Came in from the Cold from the library. That's the novel that brought him international fame and it's one of the best books in the spy genre.