Stilton and his young assistant, Nat are called on to solve a crime - the theft of 12 precious items from the city museum. At every place they visit, they must solve a puzzle - either problem-solving, questions of logic, or hunt-and-find - leaving the reader clues to guess the identity of the thief.

Another crime for the great Inspector Rockfort to solve! A Countess�s precious stones have been taken from her hotel room, and local police have concluded that one of the hotel�s other guests did the deed. So, Rockfort inspects the seaside resort, looking for jewelry among the cheerfully colorful carousels, greenhouses, and candy and shell shops chock-a-block with goods. But he can use some help, and that�s where kids come in. They have to go through the drawings, searching carefully for the Countess�s missing jewels in each one, and solving fun riddles. By the end, Rockfort and his team of puzzle-loving readers will have figured out whodunit and cracked a tough case.