Murder in Mesopotamia By Agatha Christie

Murder in Mesopotamia is a work of detective fiction

Dr Erich Leidner is, ostensibly, a Swedish archaeologist on a dig near Hassanieh, Iraq, then a British protectorate. A middle aged man, he is married just two years to a beautiful woman. His wife Louise was married briefly during the Great War 15 years earlier in 1918, to a German named Frederick Bosner, a young man who worked for the U.S. State Department, but was actually a spy for Germany. He was caught, tried and sentenced to death. He managed to escape while he was being transported. It was to no avail as he ended up on a train that crashed; a body bearing his identification was found in the wreckage.

Amy Leatheran is a nurse working in Iraq when she meets Dr Leidner. He asks her to join the dig to look after his wife. Mrs Leidner has been frightened by weird goings on, such as a ghostly face appearing just outside her window one night and threatening letters. She confides to Nurse Leatheran that she had received similar threatening letters several years before that were worded as if written by her dead first husband. They arrived every time she would go out with a new man, then stopped when she broke off the relationship. One of the letters was signed with her late husband's name. She had no letters from him from their short marriage, so she could not ascertain whether the letters were really written by him. No letters arrived when or after she met and married Dr Leidner, and had hoped that experience was behind her. Its recurrence at the dig scares her badly.