It started with a kidnapping-seven members of the Cahill family were snatched by an organisation known only as the Vespers, who have demanded a series of bizarre ransoms from around the world. Dan and Amy Cahill continue their global treasure hunt, determined to bring back what Vesper One needs. But when they deliver the last ransom, Amy and Dan discover Vespers One's terrifying endgame. The objects he demanded are vital pieces in a Vesper Plot that will harm millions of innocent people. Now the siblings and their friends are in an all-out sprint to stop Vesper One . . . before the whole world goes BOOM!