As she unpacks in her new bedroom, Ella is irresistibly drawn to the big old house that she can see out of her window. Surrounded by overgrown gardens, barbed wire fences and 'keep out' signs. It looks derelict. But that night a light goes on in one of the windows. And the next day she sees a girl in the grounds. Ella is hooked, the house has a story to tell, she is sure of it. Enter Thornhill, Institute for Children, and discover the dark secrets that lie within.