TONG SHAP-YAT enters the underground boxing scene for money and learns Thai boxing with his brother KO WAI-TING in Thailand, a decision he regrets for the rest of his life. In order to turn over a new leaf, he withdraws from the boxing scene and finds himself a job as a security guard at a sports goods company. His outspokenness attracts the attention of his supervisor CHAI PAK-FAI.
Tong Shap Yat was a devoted adherent of Muay Thai. To prove himself against the best, he fought in underground matches in Thailand, and accidentally kills an opponent. Jailed for manslaughter for years, Tong returns to Hong Kong a changed man. His wife had died from illness, leaving Tong a lone parent/sole provider for his son. A remorseful Tong attempts to wash his hands of Muay Thai and seeks to lead a peaceful life.
Ko Wai Ting is Tong Shap Yat's friend and students in the same Muay Thai gym. Over the years, Ko has built a successful Muay Thai business, on the success of his own and his stable of fighters. With his stable depleted by injuries/defections, Ko attempts to convince Tong to return to the ring. The prize money will allow him to better provide for his son.
Pat Ka Shing is saved by Ko Wai Ting from a beating. He joins Ko's gym to learn to protect himself. Pat is persuaded to fight in competitions, and Muay Thai giving him a purpose/direction in life that he had lacked.