England, 31st August 1939: the world is on the brink of war. As Hitler prepares to invade Poland, thousands of children are evacuated from London to escape the impending Blitz. Torn from her mother, eight-year-old Anna Sands is relocated with other children to a large Yorkshire estate which has been opened up to evacuees by Thomas and Elizabeth Ashton, an enigmatic childless couple. Soon Anna gets drawn into their unravelling relationship, seeing things that are not meant for her eyes — and finding herself part-witness and part-accomplice to a love affair, with unforeseen consequences.