The Maze of Bones by Rick Riordan
Siblings Amy and Dan Cahill attend their grandmother's funeral and recieve a challenge: find the 39 clues. This sends them around the world to serch for the clues that will lead to world domination as the prize. But as the youngest competitors, can they survive?
"You have been chosen as the most likely to succeed in the greatest, most perilous undertaking of all time - a quest of vital importance to the Cahill family and the world at large . . ."
Visit http://www.the39clues.com/ to learn more and join in the search for the 39 Clues.