Angels in the Gloom – Anne Perry
In March 1916, Joseph, a chaplain at the front, and his sister Judith, an ambulance driver, are fighting not only the Germans but the bitter cold and the appalling casualties at Ypres. Scarcely less at risk, Matthew, an officer in England’s Secret Intelligence Service, fights the war covertly from London. Only their sister Hannah, living with her children in the family home in tranquil Cambridgeshire, seems safe. Appearances, however, are deceiving.