Last post / by Robert Barnard.

Enhanced descriptions from Syndetics:

A mysterious envelope arrives on Eve McNabb's doorstep soon after she has buried her mother, a woman who kept many secrets. The puzzling letter inside this envelope hints at an illicit passion between the letter writer and Eve's mother, May McNabb. Even when she was a child, Eve sensed that there were parts of May's life she would never understand. She would never know the details of her parents' marriage or why her father suddenly disappeared from her life. While Eve has always believed that her father was dead, she begins to wonder whether her mother's life as a widow had been a ruse. Will she have to question everything her mother has told her? Could her father be alive and well? The letter writer may have some answers, but how can Eve find him or her? With only a blurred postmark for a clue, Eve sets out to locate the writer and journey into her own past. What she never suspected was that questions can be dangerous, perhaps even deadly... Filled with piercing wit and illuminating insight into the human condition, Robert Barnard's Last Post proves yet again that he is one of the great masters of mystery.