Byeong-Goo (Um Tae-Goo) was once a promising professional boxer. A mistake he made ended his career. He now makes a living by doing small jobs at a gym run by Mr. Park (Kim Hee-Won)). Byeong-Goo wants to make a comeback in the boxing ring, but he is diagnosed with punch-drunk syndrome (CTE). One day, Min-Ji (Hyeri) comes and joins the gym. She sees Byeong-Goo’s passion for boxing and supports him. With Min-Ji’s support, Byeong-Goo decides to complete his own peculiar boxing style “Pansori Boxing” and he begins his reckless challenge.