In the wake of a deadly storm, past sins return to haunt the living... Eilean Eòin is a tiny scrap of land which is stranded amidst miles of fierce ocean, where the scant population barely cling to a centuries' old way of life. It is here that Flora McKinnon, an aging islander, is brought news of her youngest child's death, whilst tensions are riled by the arrival of a new reverend, Thomas Murray. Murray has a mission: to weed out religious dissent and purge the island in the name of progress. When a strange young woman is found washed up on the foreshore, illness and famine start to blight the island, stirring whispers of witchcraft. Despite their differences, Flora and Murray unite in an uneasy attempt to solve the mystery of the girl's identity, which soon becomes an all-consuming obsession. With their own deep-buried skeletons, will the island's dark secrets make or break them both?