One exciting event follows another when Frank and Joe Hardy are hired to apprehend the pickpockets who have been plaguing Solo s Super Carnival. When their friends Tony Prito and Biff Hooper exhibit a stuffed whale dug up at a construction project, they all but put the carnival out of business. In this thrilling mystery the young detectives pit their wits against a gang of thieves whose bizarre identification, a three-part whale tattoo, proves to be a nearly insolvable riddle."