In the vibrant city of Shanghai in 1908, Chen Zhen returns to his cherished Jingwu School with dreams of marrying his beloved, Yuan Li'er](/actor/nora-miao). However, his joyful homecoming is abruptly marred by the devastating news of his revered master, Huo Yuanjia, having passed away. As he grapples with this heart-wrenching loss, the somber funeral is disrupted when a group from a Japanese dojo in the Hongkou District arrives, bombarding the Jingwu students with insults and disdainful taunts.
Among them, Wu En, the interpreter for Grandmaster Hiroshi Suzuki, escalates the provocation by striking Chen across the face multiple times. This act of aggression pushes Chen into a corner, igniting a fierce desire for retribution against one of Suzuki's students. The Japanese students further disgrace Jingwu School with a banner that reads "Sick Man of East Asia," a disgrace to both the memory of Huo Yuanjia and the integrity of Chinese strength. The accompanying challenge dares any Chinese student to fight, vowing they'll be defeated. Although the senior student, Fan Junxia, cautions restraint, Chen's resolve to retaliate strengthens.
In an act of sheer courage, Chen decides to confront the Japanese head-on and goes to the Hongkou dojo to reclaim the insulting banner. What follows is a series of remarkable triumphs for him against the Japanese students, culminating in the defeat of their sensei. Demonstrating his defiance, he smashes the glass around the banner, forcing his enemies to "eat their words" by making them consume the humiliating message.
Later, Chen finds himself at a nearby park but is turned away due to a discriminatory notice forbidding Chinese people from entering. When a foreigner is allowed entrance with a dog, his frustration boils over, especially after being told by a Japanese man to act like a dog to enter. In a fit of rage, Chen unleashes a powerful beating on the provocateur and his friends.
As tensions escalate, Chen destroys the objectionable sign, leading to the Sikh guard sounding an alarm. Yet, amidst the chaos, the community rallies around Chen, aiding in his escape from the authorities. In retaliation for his actions, the Japanese students, under Suzuki's orders, launch an attack on Jingwu School. Their warning demands Chen's surrender to face punishment for his supposed misdeeds.
As Chen's return to Shanghai unfolds, he begins to realize the turbulent havoc his actions have unleashed. Faced with the grim possibility of facing justice from the Japanese, his friends devise a daring plan for his escape. Under the cover of night, Chen uncovers a shocking betrayal: the poisoning of Master Huo was perpetrated by Tian, the cook, and Feng Guishi, the caretaker. Seizing this moment of vengeance, he eliminates both traitors and hangs their bodies in a public display of retribution.
In the meantime, Suzuki's attempts to capture Chen are thwarted, as he slips past Inspector Lo, who is pressured by Suzuki. While entertaining a visitor, Petrov, Suzuki learns of Chen's ruthless assault on Wu, who he gruesomely displays. Enraged, Suzuki rushes to the Japanese Consulate to report and orders his men to eliminate everyone at Jingwu School.
That fateful night, Chen storms into the dojo seeking vengeance, leaving a trail of blood as he confronts Yoshida, Petrov, and Suzuki. In the aftermath, he returns to Jingwu School only to find devastation; many students lie dead, but Yuan, Fan, and Xu have survived, guided by a tip about Chen's location.
As Inspector Lo arrives, Chen resolves to surrender for the sake of his master's honor. Lo reassures him of their shared bond as Chinese comrades. However, as they exit, they are met by armed Japanese soldiers and Western officers, all aiming their weapons at Chen. Fueled by righteous anger, he charges forward, performing a spectacular flying kick before being felled by a barrage of bullets. In a haunting moment, the scene freezes, capturing him in mid-air as he faces his tragic end.
