In the Line of Duty 4

皇家師姐IV直擊證人

Also known as In the Line of Duty IV, Wong Ka Si Sei IV: Sik Gik Sing Yan, Wong gaa si ze IV - Zik gik zing jan, Huáng Jiā Shī Jiě Sì Zhí Jī Zhèng Rén, In the Line of Duty 4: Witness

Two detectives who are up to their necks in trouble and in each other's face, as they try to shut down a drug-trafficking scheme that could be connected with international ties to organized crime. But in the midst of their investigation, innocent immigrant dock worker Luk Wan-Ting gets caught up in the mix when he witnesses the murder of an intelligence operative and is framed for the crime.