"Dan Cahill is NOT a ninja. But try telling that to him. Especially since he learned that his family--the Cahill family--is the most powerful group of people in the world. All he has to do now is to find the 39 Clues hidden around the world that lead to the source of the family's power. That is, if rival family members don't kill him first. Dan better learn how to use his nun-chucks. He's going to need them."