39 Clues: Unstoppable

The Cahill family has a secret. For five hundred years, they have guarded the 39 Clues – thirty-nine ingredients in a serum that transforms whomever takes it into the most powerful person on earth. If the serum got into the wrong hands, the disaster would rock the world. So certain Cahills have always made it their mission to keep the serum safe, buried, locked away. Until now. Thirteen-year-old Dan Cahill and his older sister, Amy, are the latest guardians of the Clues. They think they've done everything right, but a tiny mistake leads to catastrophe. The serum is missing and Dan and Amy have to get it back and stop who stole it... before it's game over. For everyone.

As a member of the most powerful family history has ever known, 13-year-old Dan Cahill has been shot at, kidnapped, and even thrown into a pit with a deadly snake. He’s survived it all due to luck, smarts, and his older sister, Amy, who always sticks by his side. Now Dan and Amy are facing their greatest threat yet, an enemy who has found a way to use the source of the Cahill family power against them. To stop him, Dan and Amy must set out on a desperate mission that will take them from one of the world’s hottest regions all the way to the frozen blast of the Arctic Circle. But with the enemy closing in, Dan finds himself facing one terror he never imagined - being betrayed by his own sister.

Life or Death The clock has run out for thirteen-year-old Dan Cahill. As head of the most powerful family the world has ever known, he and his older sister, Amy, have been in the crosshairs for too long. Dan and Amy have always managed to stay a step ahead of their enemies, but it was only a matter of time until luck failed them.Now Dan is hopelessly trapped and nothing can save him. Nothing except unleashing an evil into the world even worse than the enemies closing in. As Dan hovers between life and death, Amy has a terrifying decision to make. Just how far is she willing to go to save her little brother?