It's New Independence Day in Rural Nebraska, five years after the completion of the Freedom Wall, a four-million square foot security blanket that enclosed the United States mainland like a fishbowl. The wall was built to keep everyone out, but now they're locked in. On this national day of celebration, America's enemies and former allies join forces to decimate the American dream, bombing airports, military bases, taking out infrastructure, and eradicating most of the population.

Fast-forward two years. Our window into this new world is Penny Wells, a teenage girl with a violent fastball, a smart mouth, and a quick temper, along with her battle-hardened ex-Army Ranger stepfather, Luke Dixon. Their relationship is like a powder-keg about to explode. Still, they share a singular focus, a singular mission: To find Penny's mother, who went missing on the day of the attacks. The landscape is barren; cities and downtowns are nothing more than rusted skeletons. Hospitals, shopping malls, and schools are overrun by wildlife. And the people... The people that remain are a mixed bag of chaos, from cannibals to marauders and slavers to psychopaths. If Penny and Luke are going to survive and find her mother, they'll need to learn to rely on one another.