Clara and her younger brother Stephen are taken by their father to stay with their aunt and uncle in a remote house in the hills as their mother recovers from an accident. At first, they see it as a summer to explore. There’s the train set in the basement, the walled garden with its secret graves and beyond it all the silent loch, steady and waiting.

Auntie has wanted them for so long - real children with hair to brush and arms to slip into the clothes made just for them. All those hours washing, polishing, preparing beds and pickling fruit and now Clara and Stephen are here, like a miracle, on her doorstep.

But the reality of two children - their noise, their mess, their casual cruelties - begins to overwhelm Auntie. The children begin to uncover things Auntie had thought left buried, and Clara can feel her brother slipping away from her. This hastily created new family finds it self falling apart, with terrifying consequences for them all.