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The Clue in the Jewel Box is the twentieth volume in the Nancy Drew Mystery Stories series. It was first published in 1943 under the pseudonym Carolyn Keene. The actual author was ghostwriter Mildred Wirt Benson.
Video The Clue in the Jewel Box
Plot
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 is living in exile in River Heights, asks Nancy to search for her long-lost grandson. Using an old, faded photo of the prince at age four, Nancy begins her search. A secret in the old jewel box helps Nancy unveil a slick impostor, and bring the mystery to its thrilling conclusion.
Source of the article : Wikipedia