Fifteen-year-old Maisy Mitcham and her twin brother Duncan lose their mother to an insane asylum one night in 1955. The twins are sent to their grandmother's country house, Nightingales. Cold and distant, she leaves them to their own devices, to explore and to grow. That is until the day Duncan doesn't come home from the woods. With their grandmother seeming to have little interest in her grandson's disappearance, and the police soon giving up hope, it is left to Maisy to discover the truth. And she will start with Grace Deville. A woman who lives alone in the wood, about whom rumours abound ...