Meg and her mother have left their London apartment and go to start a new life in the country and Meg is unhappy. One afternoon Meg hears the voice of a child calling her from the garden. Following the child's pathetic calls, she unearths a toy horse with an obsidian mirror in its forehead. Through this mirror, Meg makes contact with Jankin, the ghost of a young boy. He tells her that he has been imprisoned for 500 years by a necromancer.. Meg feels sorry for him and promises to release him. But is Jankin is the innocent child he appears to be? Or is something or someone more powerful at play?