"Thirteen-year-old Dan Cahill and his sister, Amy, thought they were safe. They're Cahills, after all--members of the most powerful family the world has ever known. But an organization known as the Vespers has been waiting in the shadows for their turn to stomp across the world stage. Now Amy and Dan are in a dangerous race to stop the Vespers that will take them through back alleys around the world. Dan and Amy better watch their backs. Because the enemy is always on their tail."