Sophie, now almost fourteen, has enrolled in school full-time, and Humphrey has left to attend his boarding school in London, which leads Sophie to make new friends. On hearing an old folk tale, Sophie investigates the school bell tower only to discover a ghostly monk named Erig, who warns of a perilous plot at the school. Suddenly, Sophie and her friends are drawn into another spooky adventure. Although, unable to handle the situation on their own, they call upon 'The Forest Knights of Suffolk' for assistance. Join Sophie in her final and most dangerous adventure yet. Will she, along with the knights, be successful in their mission to save the school ... ? And will Sophie survive the impending danger ... ?