By the year 2024, environmental degradation and economic collapse have all but destroyed American society. Diseases like measles ravage the population, people fight and die over water, and new drugs corrupt the survivors. The only safety is found in walled communities like the one Lauren Olumina lives in with her family - enclaves where suburban families have come together to survive. Lauren is a minister's daughter, but she does not share her father's faith and has invented her own religion: Earthseed, which teaches that God is change.
Despite the safety of the neighborhood, there are few prospects there: there are few jobs left, and the houses become more and more crowded as more babies are born. Additionally, the thieves and gang members outside become more bold, sneaking in to steal the fruit, livestock, and other items belonging to the people of the neighborhood. Lauren insists that the people of the neighborhood must develop a plan if the walls that protect them ever fall, but, because of her youth, her suggestions fall on deaf ears.
The only hint of a future - albeit a dark one - comes from the town of Olivar, which gave itself up entirely to a company called KSF in order to gain assistance stopping the erosion of its coastline. Though this seems like a haven of safety and possibility, Lauren and her family know that they will have to allow the company to control every aspect of their lives.
Still, the appeal of such safety is apparent when Lauren's oldest brother Keith is murdered by the gang members he has befriended, and when her father goes missing. Not long after, the neighborhood is attacked and invaded - the houses are burned down, and Lauren's stepmother and brothers are killed. Lauren and two other survivors of the neighborhood, Zahra and Harry, start to head north, where water is more plentiful and jobs are easier to find. On the way, they take in more outcasts: Natividad and Travis, an interracial couple; Jill and Allie, two young women who were forced into sex slavery by their father; Bankole, a former doctor with whom Lauren falls in love. When they reach the north, they establish their own community, Acorn, based on the tenets of Lauren's religion, Earthseed.