Macau's former Muay Thai champion Bruce Chung (Louis KOO) runs a boxing gym "Chung Lui Society" and is committed to his philosophy of never backing down from a challenge. After businesswoman Elsa Lam (Louise WONG) clashes with retired actress Carrie MOK (Gigi LEUNG) at a shoot, she discovers that her boyfriend Daniel Wu (CHAN Charm Man Peter) is cheating on her with Macau's Muay Thai female champion Surewin (Chrissie CHAU). The ladies get dragged into a brawl that goes viral online and competitive Elsa challenges Surewin to a real fight, in the ring. Under the rigorous training of Bruce and devoted student Stallone (Tony WU Tsz Tung), Elsa realizes her motivation actually lies in her own personal growth. Inspired by Elsa, Bruce finally agrees to compete with his former protégé, Arnold CHAN (German CHEUNG), after their earlier falling out. Carrie's newfound fame gives her an opportunity to make a comeback as an action-film star, forcing her to join in on the hellish training led by her husband Bruce. On the day of the match, everyone steps into the ring for an ultimate showdown.