The 39 Clues is a series of adventure novels written by a collaboration of authors, including Rick Riordan, Gordon Korman, Peter Lerangis, Jude Watson, Patrick Carman, Linda Sue Park, Margaret Peterson Haddix, Roland Smith, David Baldacci, Jeff Hirsch, Natalie Standiford, C. Alexander London, Sarwat Chadda and Jenny Goebel. It consists of four series, The Clue Hunt, Cahills vs. Vespers, Unstoppable, and Doublecross. They chronicle the adventures of two siblings, Amy and Dan Cahill, who discover that their family, the Cahills, has been the most influential family in history. The first story arc concerns Dan and Amy's quest to find the 39 Clues, which are ingredients to a serum that can create the most powerful person on Earth. This series' primary audience is age 8–12. Since the release of