A guide to the characters and situations in "The 39 Clues" series, outlining the Cahills' secrets, including hidden facts, strategies, agents, lost founders, secret bases, and scandals, as well as information about all branches of the family.

This book explores the hidden facts, dangerous missions, top agents, and secret hideaways of the five branches of the Cahill family and their desperate hunt for the thirty-nine clues that will lead them to the secret of world domination.