Director: Yuen Woo Ping
Cast: Cynthia Khan, Donnie Yen, Michael Wong, Yuen Yat Chor
Production Year: 1989
Duration: 94 mins
In the Line of Duty 4 sees Cynthia Khan ride on her success, reprising her role as Madame Yeung, following her debut in the previous film of the series.
Sent to Seattle to assist in the investigation of a drug trafficking scheme, police detectives Madame Yeung (Cynthia Khan) and Detective Donny's (Donnie Yen) volatile working relationship doesn't seem to be getting them anywhere. In the midst of their investigation, innocent migrant dockworker Luk (Yuen Yat Chor) gets caught up in the mix when he witnesses the murder of an intelligence operative and is framed for the crime.
As Luk flees to Hong Kong, Madame Yeung and Donny follow the fugitive, with the aid of police officer, Michael (Michael Wong). As the investigation continues, Luk's claims of innocence begin to appear true, and the detectives soon realise that the true culprits of the crime are a lot closer than they thought.