In the annals of espionage, one name towers above all others: that of H.A.R. “Kim” Philby, the ringleader of the legendary Cambridge spies. A member of the British establishment, Philby joined the Secret Intelligence Service in 1940, rose to the head of Soviet counterintelligence, and, as MI6’s liaison with the CIA and the FBI, betrayed every secret of Allied operations to the Russians, fatally compromising covert actions to roll back the Iron Curtain in the early years of the Cold War.