In 1955 the British foreign secretary stood up in the House of Commons and publicly cleared a man named Kim Philby of being a Soviet spy. Philby followed up with a charming press conference in his mother's living room, looked into the cameras, and lied. He had been a Soviet agent for more than two decades, and his own service had effectively helped him get away with it. This episode is a deep dive into the Cambridge Five's most damaging member and the institution that produced him.

We trace his path: Westminster, Cambridge, the radicalization of his Trinity College circle (Burgess, Maclean, Blunt, and Cairncross), and the patient cover identity he built as a foreign correspondent during the Spanish Civil War. We unpack his rise inside MI6, his liaison role in Washington with the FBI and CIA, and the catastrophic damage he inflicted o ...