Enemies from the evil empire of Nastonia are invading the country. Read the book to find the hidden numbers, then open the lock and enter the secret world of spies. Challenge your skills with brain benders, quests, maps and missions. As you explore this top secret adventure, you'll move up the ranks from cadet to full-fledged agent. You have to crack a code to get to the inside hidden compartment of the book. Inside there are various missions that you can succeed in only by following instructions and completing various activities which include word puzzles and fun science projects. The only drawback is that once you solve the missions, you're done. It's not something you would do twice. Ideal for 7 year-olds or younger (say, to age 4). Kids will love the locked box because you can reset the combinatiuon code and it will be a truly secret place that only they can enter.