| Director | Fruit Chan |
|---|---|
| Budget | $150 million |
| Box office | $12 million |
Undercover police officer Kowloon concludes his mission to arrest mafia boss Uncle when they engage in a fight at a hotel. The violent altercation gets captured on video and posted online, leading to significant backlash. As a result, Kowloon's superior reassigns him to a remote police post in Yuen Long. Soon after, a serial murder case emerges in his new jurisdiction, targeting female police officers. Kowloon's superior promises to reinstate him if he solves the case, prompting Kowloon to set a trap using female subordinates as bait. Unfortunately, the murderer outsmarts the police and kills two officers, including Kowloon's fiancée, Fong Ning. Devastated by her death, Kowloon resigns and turns to underground boxing.
Years later, Chow, Kowloon's former partner, finds him and informs him of a serial murderer in Macau using similar methods to kill policewomen. Assigned to cooperate with the Macau police, Chow recruits Kowloon for the investigation, knowing he seeks revenge for Fong's death. Kowloon agrees and investigates one of the crime scenes, discovering a deflected bullet from a stolen Hong Kong police pistol belonging to his deceased colleague. When he plans to investigate the victims' homes, he realizes he is being followed by a woman. Chow also discovers he is being surveilled at his hotel. They decide to enlist the help of Kowloon's friend, Mung-kei, who quickly assists them in evading their followers. However, a Macau police detective, Tso, confronts them and reveals that he is the one who sent his men to monitor Chow. Upset with their unauthorized investigation, he sends them back to Hong Kong, but Chow's superior continues to press them to solve the case within an additional half-month.
Kowloon identifies the woman tailing him as Lady, a renowned personal trainer in Macau and the wife of Alexander Sinclair, a former American soldier-turned-boxer whom Kowloon fought before. Kowloon requests Chow's men to monitor Lady during her visit to Hong Kong, and they overhear a call revealing that Sinclair is behind the serial murders. However, when police raid Lady's mansion, she fiercely resists and fatally shoots Chow. Enraged, Kowloon pursues Lady, and they fight on a light rail, leading to an accident that causes the train to derail, resulting in Lady's death.
The following day, Kowloon receives a package containing Fong's corpse. Sinclair then confronts Kowloon, explaining his hatred for policewomen stems from losing a fight to Kowloon and the ensuing mockery by policewomen, which leads to his son's accidental death in a car crash. The two fight, with Kowloon gaining the upper hand, but Sinclair jumps out of a window and vanishes. Desperate, Kowloon prays to the nine-headed dragon from his childhood, asking for its aid if it is real.
Sinclair later calls Kowloon, falsely claiming he has abducted Wong. When Kowloon arrives at Sinclair's gym, Sinclair reveals he has lied and Wong is safe, but challenges Kowloon to a death match. As Sinclair struggles in the fight and attempts to flee on a speedboat, the nine-headed dragon answers Kowloon's call, blocking Sinclair's escape and dragging him back to shore. Although the police do not witness the dragon, Kowloon solidifies his belief and expresses his gratitude to it.