39 clues - book four - beyond the grave - SCHOLASTIC

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, canAmy 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.