It is the summer of 1942, and after two difficult years, DI Tom Tyler is making a fresh start in Ludlow, Shropshire. On the outskirts of town, St. Anne's Convalescent Hospital, staffed by nursing sisters who are also Anglican nuns, has been established in an old manor house to help victims of the war. But their peace is shattered when a horrifying double murder is discovered on the grounds. Tyler must discover how the crime was committed in such a secluded place, where most of the patients are unable to walk, and many are deeply traumatized. When he begins to receive mysterious letters recounting terrible crimes, he realises that he is not only seeking a murderer, but that the horrors of the war are closing in on this place that was meant to be a refuge.