Sit back and buckle up. This exciting fourth entry in the groundbreaking multimedia series is nothing less than an edge-of-your-seat thriller!
A clue found in Book 3 sends Amy and Dan jetting off to find out just what's behind the fierce rivalry between the Tomas and Ekaterina branches of the Cahill family. Was a Clue stolen from the Tomas branch? Where is it now? And most important, can Amy and Dan get their hands on it before their rivals do? It's a wild race that will take Amy and Dan deep into the bowels of the earth .... and right into the hands of the enemy.