Sorry For The Dead by Nicola Upson

At once a compelling murder mystery and a moving exploration of love and grief, critically acclaimed author Nicola Upson's eighth Josephine Tey mystery is a force to be reckoned with. In the summer of 1915, the sudden death of a young girl brings grief and notoriety to Charleston Farmhouse on the Sussex Downs. Years later, Josephine Tey returns to the same house--now much changed--and remembers the two women with whom she once lodged as a young teacher during the Great War. As past and present collide, with murders decades apart, Josephine is forced to face the possibility that the scandal which threatened to destroy those women's lives hid a much darker secret.