Into the Gauntlet: 10 (The 39 Clues)

Throughout the hunt for the 39 Clues, Amy and Dan Cahill have uncovered history's greatest mysteries and their family's deadliest secrets. But are they ready to face the truth about the Cahills and the key to their power? After a whirlwind race that's taken them across five continents, Amy and Dan now face the most the difficult challenge yet - a task no Cahill has dared to imagine. When faced with changing the future of the world, can two children succeed where 500 years' worth of famous ancestors have failed?