The 39 clues

The 39 Clues is a book series and online game about a hunt with the protagonists a 14 years old girl, named Amy Cahill and a 11 year old boy named Dan Cahill. The Cahill family are getting clues by clues.. leading to a power.

The 39 clues have a category, The 39 Clues (http://wiki.answers.com/Q/FAQ/8015)