On a rainy night in the city, Captain Wong Kun, Wu Hsing-Guo and his colleagues celebrate the prospect of training in Beijing, a moment of relief that quickly gives way to a deadly clash of loyalties. When Shum Chi-Hung and his crew, the infamous Chun-Lei Red Scarf, seek revenge, they strike hard and take the life of Wong’s mentor, turning a quiet celebration into a grim confrontation that sets the whole case in motion.
The Red Scarf have earned a fearsome reputation across Shenzhen and Hong Kong, and one fateful evening they descend on Mongkok to rob a Mahjong school. Nearby, Inspector Hung, Anthony Wong, selling gramophone records, is drawn into the gun battle. The incident catches the attention of the Information Bureau, and Hong Kong’s authorities direct Hung to Shenzhen to work alongside Chinese police to bring the Red Scarf to heel. The uneasy alliance between two policing worlds begins to form as Hung and Captain Wong join forces, their methods sometimes clashing yet gradually aligning in pursuit of a common target.
The hunt leads them to a nightclub, where a tense confrontation ends with the Red Scarf escaping back across the border into Shenzhen. Their approach and philosophies differ enough to cause friction, and Hung even asks to leave Shenzhen. Yet he remains integral, helping Wong piece together codes and clues that could crack the gang’s operations before he ultimately steps back. The investigation widens as Chi-Hung’s girlfriend, Hou-Yee, travels to Shenzhen to deliver money and forged passports at Chi-Hung’s request. Both Hong Kong and Chinese authorities pursue her, and the two sides deliberately disrupt each other’s plans to gain the upper hand.
Hou-Yee, Carrie Ng Ka-Lai, is not just a pawn in the criminals’ scheme—she is tied to Captain Wong as his former girlfriend, a detail that weighs heavily on Wong as events unfold. Wong hopes to shield her, yet when Hou-Yee encounters Chi-Hung, the tension explodes into tragedy: Chi-Hung kills her, asserting that she still remembered Captain Wong even as she tried to stay safe.
Meanwhile, Chinese police close in on Chi-Hung, and Hung’s boss, William Duen Wai-Lun, grows furious at how the Hong Kong officers have handled the operation. Diplomatic pressure eventually forces Chi-Hung’s repatriation back to Hong Kong, where he is escorted under heavy guard. The high-stakes transport becomes a perilous mission as Chi-Hung’s gang ambushes the pair, kidnapping Hung and forcing a dangerous crossing of borders.
In a desperate bid to rescue his ally, Captain Wong crosses the border and engages in a brutal gunfight with the criminals. The pursuit culminates in a rural village in Hong Kong, where Wong’s determination prevails and Chi-Hung is killed, marking a hard-won finale to a case that tested loyalties, protocols, and the boundary between two police worlds. The story closes with a hard-won sense of closure, tempered by the personal costs borne by those who chased a dangerous and elusive criminal network through a city’s rain-soaked nights.
