This multi-author middle-grade adventure series follows two orphaned siblings who discover their family is part of the most powerful secret network in human history — and are given a choice between a cash prize or the chance to hunt for 39 clues hidden around the world that together reveal the source of the family's extraordinary power. The series combines globe-trotting adventure, historical mystery, and a collectible card game element across ten main books written by different authors.
Siblings Amy and Dan Cahill are thrust into a dangerous global race to collect 39 Clues hidden around the world that, when combined, will reveal the source of the Cahill family's extraordinary power a secret that has shaped history. The first book in a fast-paced adventure series blending historical puzzles with thriller action, set in motion when their grandmother is murdered. Accessible, exciting, and designed to spark historical curiosity.