When Rosie Churchill moves into the beautiful but run-down Castaway House in the seaside town of Helmston in 1965, she uncovers a scandal that has been hidden for nearly half a century.

Robert Carver lived at Castaway House in its 1920s heyday, when it was the seaside home of a wealthy but damaged family caught up in a tragic case of mistaken identity, heartbreak and a suspicious disappearance.

Trying to bury her own difficult past, Rosie is looking for a fresh start. But the more she learns about Robert Carver, the further she is drawn into the mysterious history of the house. And the more their stories, old and new, entwine.