It is Christmas 1937 when Rowan and Thea travel from London to Scotland to visit their dying father. Having lost their mother in a tragic sailing accident when they were young, the sisters are accustomed to grief. But they have no idea that their father's death will expose a terribel deception... For back in London is his wife Sophie and their two sons. Neither family knows of the other's existence, and when news reaches Sophie of her husband's death her whole world is turned upside down. Meanwhile, Rowan's marriage is crumbling, and Thea reluctantly finds herself drawn into an act of betrayal. But, with the onslaught of World War II, their lives change for ever and they must confront the secrets between them before they can seize their chance of happiness...