Kim Philby was the greatest spy in history, a brilliant and charming man who rose to head Britain's counterintelligence against the Soviet Union during the height of the Cold War, while he was secretly working for the enemy. Nobody thought he knew Philby like Nicholas Elliott, Philby's best friend and fellow officer in MI6. But Philby was secretly betraying his friend. Every word Elliott breathed to Philby was transmitted back to Moscow, along with those of James Jesus Angleton, head of the CIA.