Sanction: A Spy Thriller by William Hunter

While in England on an unsanctioned assignment, Sean Garrett witnesses the shooting of a distinguished Cambridge professor by elite contract killer David Laurent. With his cover blown, Garrett is on the run from an assassin desperate to erase his tracks, and authorities who believe he is responsible for the murder. Banastre Montjoy, a burned-out head of section at the Secret Intelligence Service, is in a race himself to discover if the scholar's death is linked to a bombing of the London Underground a year earlier. Montjoy's nemesis, the power-hungry and scheming Berwyn Rees, seeks to drum his rival out of MI6, while maneuvering to become deputy chief. With time running out, SOG operators are sent in by the CIA to locate and extract Garrett. As Laurent, MI5, and Scotland Yard close in on their target, Montjoy uncovers a devastating secret, one that someone inside the British government has sought to keep buried since World War II.