Beyond the Grave (The 39 Clues , Book 4) by Jude Watson

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. About the Author Jude Watson is the author of the bestselling Star Wars: Last of the Jedi and Jedi Quest books, the most successful licensing series of all time.