John Bingham, model for John Le Carre's George Smiley, began a new spy series in the mid-sixties in England. as with Le Carre's spy world, this book follows a young agent one his first assignment, which ends up with him Russia.
His boss back in England (which like what Bingham himself did its for MI5, works to get him but there is a catch and that may help MI5 catch a double agent in their own ranks.
This is the real world of espionage, no 007 here. The scenes in the Russian prison, seem to be taken from actually events, with the KBG playing their sometimes double psychological games to break their opponets will.
Very good beginning and although dated for the times shows the Cold War in another light.