Cha Woo-sol, once a target of unyielding school bullying, took a drastic step when he snapped and stabbed his abuser, resulting in a prison sentence. While incarcerated, he encountered Jung Do-hyun, a former MMA champion, who became his mentor, teaching him the skills to fight and survive. After his release, Woo-sol is resolved to move on from his past and chase his aspiration of becoming a professional mixed martial arts fighter. He trains rigorously, aiming to carve out a new future despite the stigma attached to being an ex-convict. His former prison companions, who are also striving to lead reformed lives, support him. Among them, Lee Won-joon stands out as he seeks to make amends to those he bullied in his past. Nevertheless, Woo-sol's attempts to lead a tranquil life are disrupted when he encounters Hyun Woo-yong. Woo-yong is a formidable and sadistic gang leader who operates a brutal underground fighting league for his own twisted enjoyment. A skilled fighter himself, he views Woo-sol as a new plaything to manipulate and exploit. Initially, Woo-sol attempts to steer clear of Woo-yong's perilous realm, but Woo-yong's unyielding pursuit and readiness to harm those close to Woo-sol compel him to act. This leads to an intense struggle for survival, with Woo-sol being pulled into the merciless illegal fighting circuit. He is no longer merely fighting for himself but also to safeguard his friends and loved ones from Woo-yong's violent syndicate.
