Sergeant Tong Fei, [Nicholas Tse Ting-Fung], is a no-nonsense Hong Kong cop. One day during a bust with his team who include Sun, [Liu Kai-Chi], Christy, [Sherman Chung Shu-Man], and Michael, [Derek Kwok Jing-Hung], Sun is shot by a fleeing suspect due to an unreliable snitch and Michael failing to act during a door breach. Sun's bulletproof vest saves him from harm. Tong berates Michael and vows to have him transferred off the team. On the same day, Tong and Sun are called to investigate a car stolen by a crew of criminals who just finished committing a series of robberies. When Tong and Sun pursue them, they get into a serious car accident involving a passing Jeep that cripples Sun. Tong shoots at the fleeing criminals, killing two of them and causing them to crash the hijacked car. The lead criminal falls into a coma. To Tong's horror, he discovers he also accidentally shot dead Yee, [Wong Sum-Yin], the elder daughter of public prosecutor Gao Min, [Zhang Jingchu], who was placed in the trunk of their car when the criminals hijacked Gao's vehicle. Unable to handle the guilt, Tong succumbs to a fog of pain. Gao, meanwhile, pours all her love and attention to her younger daughter Ling, [Wong Suet-Yin].
Three months later, the lead criminal Cheung Yat-Tung, [Philip Keung Ho-Man], awakens from his coma. Gao Min, who had been working hard on bringing him to justice, insists he stand trial immediately. However complications arise as Ling is suddenly kidnapped by a man seriously damaged in one eye known as Hung King, [Nick Cheung Ka-Fai], who does shady jobs for hire and has his own agenda. Gao is threatened by the kidnapper to change evidence for Cheung's trial to get him acquitted. Tong is once again thrust into a cat-and-mouse game to not only save Gao's other daughter but also as redemption from his past mistakes.
Tong tries at first to enlist Gao's assistance but Gao outright refuses claiming she would rather have any other cop save Ling but not Tong as his appearance constantly reminds her of Yee. Tong's investigation goes off the books and leads him to a garbage centre where he discovers the kidnappers' SIM card. Tong is forced to turn to help from Christy and then Michael, who at first refuses to cooperate because of Tong constantly writing bad reports about him in the past and also revealing that Michael is also Tong's cousin. After Tong apologizes for his actions in the past, Michael eventually relents and assists Tong track the SIM card and also Gao's MMS and contact with the kidnapper revealing Ling is being held in an apartment with Neon Lights nearby.
As Tong and Sun try to pinpoint Ling's location. Sun goes for a lunch break in a restaurant but coincidentally spots Hung in the same restaurant Sun tries to discreetly alert Tong but Hung catches on and flees. A lengthy chase ensures where Tong attempts to Hung, but Hung's fighting skills overpower Tong and disarm him of his weapon. Gunshots from Tong's sidearm attract the attention of multiple Hong Kong PTU officers who gave chase, however Hung is able to evade all the officers in his way. Tong catches up with Hung, but Hung runs into a nearby armored car and knocks out a security guard commandeering his shotgun and pinning down Tong and the pursuing PTU officers. Haunted briefly by Yee's death, Tong eventually leaves cover and attempt to apprehend Hung but finds that Hung has disappeared and vanished from the scene.
Soon after, Tong is forced to surrender his sidearm, pending an officer involved investigation. Gao hears the news and arrives on scene. Tong reveals to Gao about the location where Ling was held. As Tong and Sun enters Hung's apartment, they discover a hidden room where they found Hung's wife whose in a deteriorative state. When Hung has taken back his wife from the police, Tong tracks him down through GPS where he finds Hung and beats him in the head with a rock. As Ling was recovered, Hung who is now fully blind, surrenders himself to the police. It was revealed that Hung was the driver of the Jeep from the earlier car accident, which results him critical injuries along with his wife. The film ends with Tong walks away with Ling as she reunites with her mother.
