Spring 1913, and seventeen-year-old Evie Murphy is leaving her native Ireland for the city of Liverpool with her baby daughter Linnet - but leaving Linnet's frail twin, Lucy, behind. These are mixed fortunes ahead for Evie, and while Lucy grows up in the beautiful Irish countryside, Linnet is all too often forced to throw herself on the mercy of the enormous, impoverished Sullivan family. Life in a slum court during the thirties is far from easy -but when tragedy strikes it becomes the only existence possible for Linnet. Destitute, she disappears into the Liverpool slums like an teardrop in an ocean. Lucy, meanwhile, urgently needs her sister by her side. But she has little idea, when she leaves the farm and sets off to look for Linnet, how their meeting will change their lives for ever.