An antique dealer's revelation about a former queen's priceless heirloom leads Nancy on a series of exciting, yet dangerous adventures. Madame Alexandra, who lives in River Heights in exile, asks Nancy to search for her long-lost grandson. Using an old, faded photo of the prince at age four, Nancy begins her search. Also, a secret in the old jewel box helps Nancy unveil a slick imposter and reunite the separated family.