1935. Norfolk. War is looming in Great Britain and the sprawling country estate of Alderberen Hall is shadowed by suspicion and paranoia. Thirteen-year-old Delphine Venner is determined to uncover the secrets of the Hall's elite society, which has taken in her gullible mother and unstable father. As she explores the house and discovers the secret network of hidden passages that thread through the estate, Delphine uncovers a world more dark and threatening than she ever imagined.