The 39 Clues will be a new book / game experience for kids aged 8 to 10.

The books will be released in September, and are slated to be authored by an assortment of popular children’s writers. The first book (The Maze of Bones, September 2008) will be by Rick Riordan, author of the Percy Jackson series, the second by Gordon Korman (January 2009), third by Peter Lerangis (April 2009), and fourth by Jude Watson (July 2009).

Each book will include six cards with codes, out of 350 total cards. Log on to the official website to play the game. Grand prize for solving the mystery is $10,000.

Steve Spielberg is already slated to make the movie.