Orkney, 1940. Five hundred Italian prisoners-of-war arrive to fortify these remote and windswept islands. Resentful islanders are fearful of the enemy in their midst, but not orphaned twin sisters Dorothy and Constance. Already outcasts, they volunteer to nurse all prisoners who are injured or fall sick. Soon Dorothy befriends Cesare, an artist swept up by the machine of war and almost broken by the horrors he has witnessed. She is entranced by his plan to build an Italian chapel from war scrap and sea debris, and something beautiful begins to blossom. But Con, scarred from a betrayal in her past, is afraid for her sister; she knows that people are not always what they seem. Soon, trust frays between the islanders and outsiders, and between the sisters – their hearts torn by rival claims of duty and desire.