In The Line Of Duty 5 (1990)

Inspector Yeung's cousin, David and his buddy Alan came to Hong Kong for a regular "Rest and Recreation". One day, Alan was killed accidentally. The secret of Alan, who was actually a spy, was thus disclosed and this led to a series of terror for both David and his girlfriend, May. David decided to seek help from Yeung. With the help of Yeung, David managed to capture the important information, but in sacrifice of May's life. In order to prove himself to be innocent and take revenge for May's death, David went to South Korea with Yeung to fight bravely! After the case was over, David realized that the whole event was a setup as he learned that CIA had been monitoring his situation all along with the objective of overrunning the intelligence organization.