In this book, Dan and Amy, with the help of their family, stopped the Vespers from starting up the Doomsday Device. This device was going to destroy the planet, but luckily, the Cahills got to it first. In this book, even Isabelle Kobra turned into a good guy, when she realized that the Vespers had killed her daughter, named Natalie. All along, Isabelle had been the ultimate villain, even shooting Natalie in the foot, at one point. I was shocked that she came to the good side. Sinead turned back from being a mole for the Vespers and ended up helping Amy and the rest of the Cahills. I was happy with how the series ended, and I'm glad that the Cahills were safe. I was worried, though, when Amy was struck by a chunk of rock in the head. She started having visions of her dead family members, and I thought she was a goner, too!
Next, I'm going to read the Infinity Ring series, which is by the same authors as the 39 Clues Books and the Cahills vs Vespers. The Infinity Ring are not books about the Cahills and Vespers, so I'm ready to meet some new characters!