The 39 Clues: The Maze of Bones by Rick Riordan

Which would you choose--a million dollars, or the chance to be the most powerful person in the world? Amy and Dan Cahill have to make the choice after their beloved grandmother dies and leaves her relatives invitations to solve the 39 clues to ultimate power or to take one million dollars. Amy is scared, and Dan really wants that million--but they decide to take the challenge just to prove to their obnoxious and evil relatives that they have the courage. Take the challeng yourself by logging onto www.the39clues.com and you may win part of the $100,000 prize yourself!