Gouzazhong, a.k.a. 'Mongrel', Philip Kwok stumbles upon a mysterious metal tablet amid a violent clash between rival martial-arts clans. A passing couple, Shi Qing and Min Rou, recognize the item and hurry to explain its significance, but the tablet is seized by the unpredictable Xie Yanke, a powerful and eccentric martial artist played by Wong Lik. Xie proclaims that he will punish the warring factions with a ritual massacre every three years, and he tempts Gouzazhong with gold, status, and even kung-fu training in exchange for the tablet. Gouzazhong refuses all offers, so Xie forces him to study kung-fu—but deliberately teaches him the wrong techniques. Gouzazhong collapses unconscious, and is found by Sun Chien, second-in-command of the Changle Gang, who brings him back to their headquarters to recover. That very night, a mysterious woman named Ding Dang, Candy Wen Xue-Er, slips into his room, acting with intimate familiarity and calling him Shi Zhongyu before vanishing with a promise to return.
Bei Haishi, the Changle Gang’s wary second-in-command, later confirms Gouzazhong as their leader in name only, once more referring to him as Shi Zhongyu despite Gouzazhong’s protests. A vengeful strike by a Changle member—intended for Shi—lands on an acupoint, granting Gouzazhong a surge of extraordinary strength. Ding Dang reappears, insisting that Gouzazhong is indeed Shi Zhongyu because Shi bears a distinctive bite mark on his shoulder; the ruse seems to be authenticated when he displays the marks again. Forced marriages loom when Ding Dang’s grandfather decrees that Gouzazhong must wed her, under the belief that Gouzazhong is the amnesiac Shi Zhongyu. Bei Haishi reveals a deeper scheme: he has long suspected Gouzazhong’s true identity but kept him close to manipulate events, including marking him while unconscious to ensure the Changle Gang’s safety if their leader refused Xie Yanke’s demands.
The Snowy Mountain School arrives in force, led by Bai Wanjian [Chan Shen], demanding revenge over Shi Zhongyu’s past actions. Gouzazhong insists he is not Shi Zhongyu, but Bai Wanjian tests him and reveals eight old sword marks on Gouzazhong’s thigh—an unmistakable sign that Shi Zhongyu once bore those scars. The tension between identities thickens as Shi Qing and Min Rou finally arrive at the Changle base; they reveal they are Shi Zhongyu’s biological parents, and that twenty years earlier their son Shi Potian was abducted and murdered by Mei Fanggu, [Teresa Ha Ping]. Bei Haishi confesses that he had known all along Gouzazhong’s true status but kept him around to serve a larger purpose. Mei Fanggu is revealed as the one who secretly raised Shi Potian, renaming him “Mongrel” to spite Shi Qing and Min Rou, and she had even swapped a dead infant for the living child to secure control.
Mei Fanggu’s influence grows as she seizes Shi Qing to drive Gouzazhong toward a deadly confrontation with Min Rou. With the Changle Gang’s help, Gouzazhong battles Mei Fanggu’s bodyguards—White Tiger Angel [Chiang Sheng], Azure Dragon [Chu Ko], and Vermilion Bird [Ricky Cheng Tien-Chi]. Bei Haishi slips away to free Shi Qing and holds Mei Fanggu at knife-point while Gouzazhong defeats the three guardians. Shi Qing shows mercy to Mei Fanggu, and departs with his long-lost son, leaving Gouzazhong to stand with the Changle Gang by his side.
The gang members, moved by Gouzazhong’s selflessness, declare him their true leader and vow to help him locate his mother. Ding Dang returns once more and engineers a risky ploy, luring Gouzazhong into swapping places with Shi Zhongyu—the real Shi Zhongyu who faces death for his crimes. Xie Yanke notices the deception, but Gouzazhong intervenes, sparing Shi Zhongyu and inviting Xie to take him under his wing for rehabilitation instead. This act cements Gouzazhong’s new, genuine role within the gang and his resolve to build a future beyond deceit.
In a climactic turn, Shi Qing asks Gouzazhong to take him to Mei Fanggu, the figure behind much of the past turmoil, who is revealed to be the mother Gouzazhong never truly knew. Mei Fanggu’s tangled history with Shi Qing and the birth of Gouzazhong come to a head as Shi Qing seeks closure and a family reunion. The finale centers on reconciliation, forgiveness, and the acceptance of Gouzazhong’s true lineage, as Shi Qing ultimately spares Mei Fanggu and departs, reunited at last with his long-lost son. The film closes on a note of cautious peace, with Gouzazhong stepping into leadership and his future framed by the complex, intertwined fates of the families and martial clans that shaped him.
