In the wake of Kim Philby's escape to Moscow, his closest friend in Britain's Secret Intelligence Service (also known as MI6.), Nicholas Elliott, is under investigation by Mrs. Lily Thomas from the Security Service (MI5): Did he facilitate Philby's escape because he's also a traitor working for the Russians, or is it just that his judgement was clouded at a critical moment by their twenty-three year friendship? Or maybe, just maybe, he in fact had the last laugh having manipulated Philby to run to the bosom of the KGB for foreign intelligence purposes.

Investigator Lily Thomas understands that Elliott is never going to divulge anything of value in a conventional interrogation process so she manipulates him.

Philby begins to understand that the KGB can never fully trust him now that he's in Moscow, and as far as they're concerned, his life as a spy for them is over.

Elliott rattles Blunt's cage to make him panic and then follows him to a clandestine meeting in the middle of the night.

Elliott and Lily fear that no one can be trusted. They must get to Blunt before anyone else to interrogate him and confirm their suspicions.

Lily has forced Elliot to remember more than he perhaps ever wanted to about Philby. Months later, Elliott receives a letter from Philby asking for a meeting in an East Berlin bar.