Smiley and his people are facing a remarkable challenge: a mole - a soviet double agent - who has burrowed his way in and up to the highest level of British Intelligence. His treachery has already blown some of their vital operations and their best networks. The mole is one of their own kind. But which one?
The first message sent to Tom Thorne's phone was just a picture - the blurred image of a man's face, but Thorne had seen enough dead bodies to know that the man was no longer alive. But who was he? Who sent the photograph? And why? While the technical experts attempt to trace the sender, Thorne searches the bulletins for a reported death that matches the photograph. Then another picture arrives.