There's a mole, right at the top of the Circus. And he's been there for years. I'm a huge Le Carre fan and I feel unless you read the book this movie version might be rather confusing. Having said that I think the movie was faithful to the book.Le Carre of course in another lifetime was David Cornwall one of the British spies who was betrayed by Kim Philby, so he knows the game here. In his mind spy game is as much bureaucratic s it is field work, thus in the movie as in the book you have a lot of British public school educated middle aged men sitting around in hushed conversations sipping tea and trying to ferret information, or get a few extra pounds to get the next phase rolling..... dealing with annoying under secretaries at the foreign office and such. Don't expect Jason Bourne , instead you get some fine acting headed by Goldman and several British veterans. Control is convinced that a mole is in place and sends Jim to Budapest to meet a man that knows, it goes wrong and in the aftermath Control and Smiley get ousted......yet Smiley gets called back out of retirement by Lacon the government undersecretary with Circus oversight after he gets a call from an agent wanting to trade..... The movie like the book is a series of flashbacks piecing the story together, I guess this is where it is hard to fit all those layers from the book into a movie.....still , I liked it a lot, I thought the characters in my mind were perfectly cast , Percy was especially well cast .....great atmosphere ,dreary cold war stuff.....