A brand new adventure from the world of The 39 Clues! After 500 years, the Cahill family's most dangerous secrets are about to be revealed. Read at your own risk . . . Fourteen-year-old Fiske Cahill thinks he's safe when he hides away on the world's first nuclear submarine . . . until he realizes there's a Vesper on board. Does he have what it takes to stand up to a ruthless enemy?