The Tigers

Lam Fong-tin leads a CID raid at the shipyard to bust firearms smuggler Sha-pei. Sha-pei provides a crucial lead about a forthcoming drug deal between Wai and Chiuchow Ping. The operation proceeds and Wai is arrested, setting the stage for a web of corruption.

Tin is shocked to discover his brother-in-law Tung is working for Wai. Tung pleads for Wai's release and leaves Tin a briefcase with HK$10 million before jumping into the water to flee. Meanwhile Thief and Dandruff stash the money instead of reporting it, while Pong refuses any share.

Tung pressures Tin; Tin and the squad persuade Pong, who arrested Wai, to give false testimonials in court to secure Wai's release. Pong reluctantly agrees, compromising his integrity. The corruption within the team begins to take hold.

Tin and the squad are forced to collude with Tung; he refuses to return the money and threatens ICAC if they don't cooperate. Tung tips the police to a new Wai–Ping deal in hopes of toppling Wai. The squad arrests Ping but lets him go free to turn him against Wai.

Ping arrives at a disco bar to settle scores with Wai, unaware that Tung tipped off the police. Thief and Dandruff lie in wait to arrest them, but Tung shoots Wai and Ping and flees to the parking lot. In the pursuit, Dandruff drops his pistol, which Tung picks up, and Thief arrives to exchange fire before Tung escapes.

Tung calls CID superintendent Cho and reveals the squad's corruption. Cho chooses to shield his underlings, while Tung threatens to report them to ICAC if they do not cooperate. The cycle of cover-ups continues to feed the downfall of the unit.

The ICAC sets a trap to arrest Tung, but Tung counters and manages to get Pong arrested by ICAC. Tin, Thief and Wah are detained by ICAC, while Pong is released without charge. Tung becomes a protected ICAC witness.

Tung is summoned to testify about murder allegations at the police station and is beaten by Pong. ICAC escorts him out, but Thief, armed with a blade, makes an unsuccessful attempt on his life and flees with the help of a colleague.

Pong bails Tin out briefly after Tin reconciles with his estranged daughter Shirley, but Tin is detained again as the ICAC investigation continues. The personal and professional lines blur as the case drags on.

To shield his squad from ruin, Tin decides to bear full responsibility for the corruption and hangs himself in his jail cell. His death shocks the remaining officers and shifts the power dynamics of the case. The ICAC presses on with the investigation.

With Tin dead, Thief, Pong and Wah head to Volvo Hotel where Tung is staying under ICAC protection to settle scores. ICAC captain Tam announces the case is closed and will hand Tung over for Dandruff's murder. Tung escapes by killing two ICAC officers guarding him, triggering a tense pursuit and confrontation.

Thief, Pong and Wah corner Tung as the SDU arrives. Thief shoots Tung dead and then shoots himself in front of the police, fulfilling his vow to bear all responsibility. Tung dies, and the survivors must live with the consequences of the case.