In Secret Decoder: The Case of the Runaway Ruby, young sleuths will love helping Gary Gumshoe find Madame Mahvelous's missing ruby! This exciting spy activity book has 18 pages of mysteries to solve. A few turns of the included decoder wheel –bound right into the book and visible from every page – will help detectives-in-training complete each challenge as they put their deductive skills to the test! To uncover even more case-cracking clues, master mazes, and complete puzzles, a "magic-reveal" pen is included, giving every page plenty of play value. It all stores neatly within the covers – perfect for spies on the go.