The 39 Clues is going to be a ten book series that will take you around the world and make you think with the clues. You can even join in on the hunt at the39clues.com. You can even collect the cards to help you on line, some have clues you must solve and others give your mind a break. For those who know the books and the online game this was posted by a Tomas. Good Luck if you join the hunt online.