The Third Encounter (Antony Maitland, #3)

Someone had murdered kindly old Dr. Martin. Scotland Yard promptly arrested Martin’s freeloading cousin Gerry, who had bumbled into an argument with his rich relative at about the fatal hour. But Antony Maitland knew Gerry didn’t do it. The good doctor had been a secret service agent… and Antony knew who really had a motive to kill him. The catch was that a visit with a man from Whitehall plunged Antony back in Her Majesty’s Service and sworn to secrecy. His only chance to save Gerry was to catch the real killer. And that desperate hunt would bring him face-to-face with a nightmare from his own past… and a wartime betrayal that had once made Antony a prisoner and now could make him a corpse. (Publisher’s description)