From the Manufacturer:
Use the decoder wheel to solve the mystery . . . then turn the page for a whole new challenge! This exciting spy activity book has 18 pages of codes to crack and whodunits to solve. A few turns of the included decoder wheel--bound right into the book and visible from every page--will help young detectives complete each challenge as they put their deductive skills to the test! To uncover even more case-busting clues, sneaky double agents, and hidden treasure, a magic-reveal pen is included, giving every page plenty of play value. It all stores neatly within the tab-close covers--perfect for spies on the go.