Five years after the zombie apocalypse broke out, Ada gave birth and turned into a sentient zombie who retained her human consciousness. She also gave birth to a son, Ethan, who likewise possessed his own thoughts. Mother and son lived in the quarantined District C, patrolling by night and rescuing trapped survivors—people called them "the Saviors."
Ada kept hidden that the boy's father was Alex, her former superior. Alex was now the commander of the human safe zone, desperately searching for Ada. Upon hearing rumors of the "Saviors," he led a team into District C. Through a series of mishaps, Ada, Ethan, and Leo—a dog that began speaking after being infected by zombie blood—were captured by Alex.
A strange green rain empowered zombies. In a moment of crisis, Ada revealed her ability to control the undead. Under the scheming Dr. Maggie's coercion, Ada was forced to remain in the safe zone, and a magical bound tied her to Alex so they could not stay apart. Ethan happened to meet Dylan, Alex's younger brother, and the truth of his parentage came to light. After misunderstandings and confronting the villains, Ada and Alex resolved the wounds of their past, and the family was finally reunited.
