A smuggler's plan to cover his kidnapping operations by stirring up old superstitions about the evil waters of the Nailbourne is foiled by Laura of Covington Castle and her clairvoyant cousin Elliot Simpson-Favorite, flesh from India. The slimy Mr. Tonner, whom the adults of Covington so imprudently trust, is aided by an underground passage that ends beneath a statue in the maze, a sudden fog that spirits away Giles the gardener from under our very eyes, and the eerie legends surrounding the Nailbourne, a network of underground streams that surface in times of drought. Like The Mystery of the Woman in the Mirror, this is inept, hocus-pocus gothic, ostensibly set at the turn of the 19th century but actually from that neverland where Daddy can be relied upon to vanquish a shipload of pirates at the last minute.