In 1996, a group of British Hong Kong soldiers, faced with the reality of their disbandment from the Hong Kong Military Service Corps and the lack of British citizenship, choose to tread varied paths in life. Among them, Kwan Chiu persuades Winston to venture into the stock market. However, as the 1997 Asian financial crisis unfolds, Winston finds himself in dire financial straits, ultimately losing his entire fortune. Consumed by despair, Winston takes his own life, leaving his former comrades to blame Kwan for his demise, severing their connections with him; unbeknownst to them, Kwan silently assumes the burden of Winston's debts to support his widow.
Years pass, and Kwan finds himself entangled with the triads. By 2019, he facilitates a deal between a Taiwanese turtle smuggler, Pickle, and the local triad leader, Big Mouth Tai](/actor/taibo). One day, a desperate young thief named Mani is chased by Tai's fierce underling, Chook, and seeks refuge in Kwan's home within the notorious Chungking Mansions. Mani presents Kwan with an offer of HK$1 million to provide him shelter for five days, a proposal Kwan reluctantly accepts. Initially, the atmosphere between them is frosty, but as Mani stumbles upon videos showcasing Kwan's heroic military past, they gradually bond. Kwan also begins to look after Mani's brother, Mansu, in his absence.
Trouble arises when Tai discovers the turtle shipment has perished during transport, prompting him to summon Kwan to reclaim his deposit. The situation spirals further when Kwan is horrified to find the lifeless body of Mani’s cousin, Kapil, executed for his previous theft of Tai's narcotics. In a grim turn of events, Mani hands Kwan a bag of drugs—their means to repay the formidable debt—and Kwan gifts Mani a hand-rolled cigarette as a symbol of their newfound camaraderie. Just when it seems like they have overcome their hurdles, Mani is snatched away by Tai's followers, shedding light on their relationship when Kwan’s distinctive cigarette emerges.
The narrative thickens as Pickle's accomplice, Bamboo, tracks Kwan down, leading him to Tai's lair where Mani is imprisoned. With tensions high, Tai, aiming to place the fault on the gravely wounded Chook, quickly enacts a new agreement with Bamboo. In a moment of fury, Kwan valiantly battles Tai's henchmen, but just as Tai prepares to deliver a deadly strike, the betrayed Chook intervenes, taking out Tai instead. In a poignant final moment, Mani rolls a cigarette for a dying Kwan, marking the first time anyone has done so for him.
Eventually, Mani approaches Kwan's former military comrades, presenting them with a note that signifies the complete repayment of Winston's burdensome debt.
