After the deaths of her adopted parents, Arran discovers her long-lost sister's name and, despite a terrifying premonitory dream, embarks on a quest to find Sheena. After reuniting in Scotland, the sisters search for the reason their birth father and his housekeeper mysteriously died and why Sheena's life is being threatened. Led to a cryptic rhyme rumored to map the way to an ancient hidden treasure buried deep in the bowels of Wraithmoor Castle, the sisters follow the clues. A murderer follows the sisters. Will the secret passages lead them to discovery and triumph, or death and eternal entombment?