A police detective must solve a brutal murder to prove his partner's innocence and unearth the truth behind Hong Kong's police force. The investigation brings him to an unlikely collaboration with an inspector from the Narcotics Bureau, whose motives may not be what they seem.

Kit (Sun Zhen Feng) is the hottest boxer in the underground boxing circuit, with over ten consecutive victories to his name. Besides his gritty determination to challenge himself, he also has a great coach (Ken Lo). In order to save their gym from being shut down, Kit agrees to a greatly hyped match with notorious Thai boxer Sholin (Zheng Ziping), who is known as a "killing machine.