One day after a zombie apocalypse. A 4-year-old child appears in front of a retired middle-aged thug and an axe-wielding nurse. It has been 10 years since human production stopped. Perhaps the only child on earth is in the hands of two men. He’s good at fighting! But not so sure about parenting?! The starting point is Busan, and the goal is a Secret Laboratory in Seoul. The two men, a cute child and a handsome man, must get to Seoul!