Ken Li is a senior member of the Hong Kong Police Force whose ego and rigid standards color both his work and his relationship with his girlfriend, Brenda. His approach is blunt, demanding, and intolerant of mistakes, which strains those around him and foreshadows the trouble ahead. The story kicks off when an Inspector is brought in to investigate a crime committed by a fellow officer. During interrogation, the implicated cop reveals he remembers nothing after meeting a mysterious man the previous night. This puzzling clue points Li toward a suspect named Jack Lai, a hypnotist who sits in jail for manslaughter after taking the rap for a murder his wife was forced to commit under duress. Jack clearly knows who is responsible, but insists that only he can identify the culprit.
Li decides to break Jack out of custody and bring him along. The risky alliance doesn’t instantly nab the mastermind, yet it uncovers a plot to steal two Egyptian diamonds worth millions from an American named Barry Lykin. Under Jack’s mental influence, Li unwittingly retrieves the diamonds from a safe, triggering a dangerous chase that brings them face to face with Officer Yeung, who pursues them through a tense sequence of events. In a parking-lot showdown, Ocean’s men engage the police in a deadly gunfight, taking several officers’ lives and Lykin’s as well. Jack seizes the diamonds and heads to Ocean, who has taken his wife hostage. Li is arrested for the alleged diamond theft, and his colleagues seize the moment to settle old scores.
A high-stakes escape follows when Li dives from the Tsing Ma Bridge to avoid recapture. His girlfriend, Brenda, still deeply in love with him, helps him stay free as they press on to pursue Jack and Ocean and recover the stolen diamonds.
Ocean remains volatile and vindictive, learning with fury that Jack has double-crossed him. To force compliance, Ocean subjects Jack’s wife and the partner’s children to a vacuum chamber ordeal, slowly running out of air. Jack returns to the scene to reclaim his wife and runs into Li. Together with Brenda, they continue the pursuit into a sprawling complex, where they split up to search for answers.
Jack desperately searches for his wife and finally finds her inside the locked vacuum chamber. Brenda is captured by one of Ocean’s men, and Li has Ocean cornered but faces a brutal choice between saving his girlfriend and stopping Ocean. In a climactic turn, Li helps Jack trigger an explosion that wipes out Ocean. The two of them retreat into a second vacuum chamber as the oxygen cylinders detonate. Jack reaches his wife, but she is mortally wounded; he lays his head on her lap as she dies. His wife comes to life slowly and sees her husband, but is too late.
In the aftermath, Li realizes there is more to life than work and begins to treat his girlfriend better.
