Twins Will and Annalie Wallace continue to search for their missing father. As the Admiralty closes in, Will, Annalie, and their friends Essie and Pod must evade capture-and pirates-while tracking Spinner's movements around the world in their small sailboat. Following a coded list, they make contact with other former scientists living undercover, and learn disturbing information about the research their father stole and its connection to the global flooding that changed their world.