Ko Shao, played by Andy Lau, is a highly skilled hitman who has just finished a contract in Shanghai and is heading back to Hong Kong. Upon his return, his boss, Ice, offers him a new assignment: eliminate Kwok Chung, a tainted witness involved in a drug smuggling case. Ice generously presents Ko with a car as a gift and offers a lucrative reward of US$300,000 for carrying out the deadly task.
Meanwhile, a newcomer hitwoman named Yu-fung, portrayed by Anita Yuen Wing-Yee, completes her first mission—killing a loan shark. During her escape, she unexpectedly bumps into Ko while fleeing from the scene. Unaware of each other's identities, Yu-fung points her gun at Ko, demanding a getaway. After escaping, she warns him that if she sees him again, she will kill him. Despite her hostile warning, Ice welcomes Yu-fung into her organization after her successful assignment.
The story intensifies with the involvement of police inspector Tung Fai, who is tasked with protecting Kwok. Tung and his team, including Dino and Wai Ma, attempt to escort Kwok to court, but are ambushed by a hitman. Tung spots the attacker and kills him, narrowly avoiding disaster. As the court session begins, Ko disguises himself as a judge, executing Kwok with precise efficiency before fleeing the scene with police in hot pursuit. Ko manages a narrow escape from Tung, who is determined to catch him.
Shortly before leaving Hong Kong, Ko encounters Yu-fung again when she gives him a ride to the airport. She warns him that she will kill him if they meet a third time, but Ko unexpectedly steps in front of her car as she drives away, claiming he will stay because she won't actually follow through with her threat. This interaction marks the beginning of a complicated relationship between the two.
Back at Ice's organization, tragedy strikes as a hitman named Yue Tung, who had failed an assignment, is mercilessly killed by Ice, who distracts him with her naked body. Ice's ruthless actions extend further when she orders her assistant, Wong Cheung, to eliminate Tung’s elderly mother. Wong kills her, along with her dog and a visiting child, revealing Ice’s cold-blooded nature.
Ko’s path crosses with Yu-fung again in a wedding, where they are drawn into a casual dinner and mahjong game hosted by a guest marriage couple. That night, they spend the night together at Ko’s home, deepening their connection. Meanwhile, Tung contacts his informant, Ma Chi-chuen, seeking intel on local hitmen. Their investigation leads them to Ko at a previously visited arcade, although Ko manages to evade their grasp. Tung later spots Ko at a disco, tries to interrogate him, but both escape their pursuers in a tense chase across a pedestrian bridge, with Ko hanging onto its side while Tung follows.
The following day, Yu-fung arrives at Ice’s art gallery to receive her next assignment. Coincidentally, she observes Ko there too, unaware they are both being watched by Ice. As they each tail their respective targets that day, their paths cross once more, and they spend a day together in secret. During this time, Yu-fung executes her own assignment at a restaurant, while Ko targets Tsui Ka Sing, a wealthy businessman played by Henry Fong Ping. Ko tries to carry out the hit during a lion dance performance at a monastery, but Tsui notices him. Both end up in a scuffle, and Ko narrowly escapes when the platform collapses, forcing him to flee in a speedboat.
Refusing to be caught, Ko offers his money back to Ice, asserting his refusal to continue as a hitman, and daring her to set a date and time for his death if she wants him dead. Ice, however, secretly tasks Yu-fung with killing Ko. In a deadly confrontation in a parking lot, Ko lures Tsui away and shoots him, but a firefight ensues when Tung and his team arrive, resulting in Ko’s escape.
Despite their differences, Ko and Yu-fung’s relationship deepens as they share intimate moments, including dinner and resting on a yacht. Ko confesses his desire to quit and escape the violent life of contract killing, fearing the repercussions Ice might unleash if he refuses. Their fragile peace is shattered when Wong Cheung kills Ice during a private moment, and later discovers Ko’s tracker embedded in his gift car. Wong and his henchmen attack the yacht, with Wong stabbing Yu-fung in the thigh and cutting off her fingers when she refuses to reveal Ko’s location.
In the chaos, Ko realizes Wong’s presence when he notices his mobile phone on Yu-fung. In a desperate act, Ko guns down Wong’s men and saves Yu-fung from her attacker, promising to leave his career behind. However, Wong doesn’t surrender; instead, a final intense gunfight erupts on the beach, ending with Wong and his men being subdued or killed, and Wong surrendering to the police. Tragically, Yu-fung, wielding Wong’s pistol, points it at Wong and the police during the confrontation. The police open fire, and both Wong and Yu-fung are killed, closing this perilous chapter in their lives.
Throughout the story, themes of loyalty, betrayal, and the struggle for redemption emerge amidst the chaos of Hong Kong’s underworld. Both Ko and Yu-fung are drawn into a web of violence they cannot easily escape, and their fates are intertwined in a tragic, action-packed saga filled with tension, sacrifice, and unresolved conflicts.
