Now a decade into the apocalypse, sisters Hope and Iris Bennett have grown up inside the walls of one of the few remaining first-world communities. The sisters' scientist father conducts research over one thousand miles away in a research facility run by the Civil Republic, an ally of Omaha, but one that does not reveal its location to outsiders. When the sisters receive a message that their father might be in danger, they defy their own community's rules and enlist their friends Elton and Silas to embark on a cross-country quest to save him. Leaving their sheltered upbringing behind, these teenagers learn how to fight threats both living and dead as they travel through a beautiful but decaying and dangerous world.