13-year-old Xiaohai is a mechanical genius, born in "Shanzhai City"—a place in the eastern part of a future island, where container houses sprawl across the mountains and fields. At that time, the robot industry was booming, and many people who built robots lost their jobs as their work was replaced by robots. They could only live in low-cost areas, forming settlements. Skilled only in making robots, driven by anger, revenge, or other reasons, they began creating knockoff robots. Over time, they thought life could go on like this. Until one day, when Xiaohai wanted to participate in the International Robot Fighting Championship, Shanzhai City was thrown into turmoil.