The 39 Clues: The Black Book of Buried Secrets

A book to save the world…

The book you see here is the ultimate source of Cahill knowledge. It contains every buried secret, every weapon or gadget, all the strongholds, and each agent and founder. Inside, you will discover the true story of Madeleine Cahill, as well as what happened after Isabel Kabra was charged with murder. Nothing has been held back.

Seven Cahill agents came together to bring you this book, betraying their branches and their most deeply held beliefs. They did it because an enemy is approaching; one far more powerful than the Cahills. Keep this black book close at all times. Be ready. Be watching. The enemy is at the gate.