In the early 1990s, a tractor mechanic, affectionately known as Steelhead (Jackie Chan), makes the daring decision to illegally enter Japan from China, driven by the urgent desire to reunite with his fiancée, Xiu-Xiu (Xu Jinglei). With the assistance of his so-called "friend" Jie (Daniel Wu), who has introduced him to the underworld's ins and outs, Steelhead embarks on a chaotic journey. While working on a clean-up crew in the sewers, their illicit activities catch the attention of the police, forcing them to flee for their lives. In a twist of fate, Steelhead becomes a hero when he saves Detective Kitano from drowning, prompting the detective to extend a surprising grace by halting his pursuit of Steelhead.
One fateful evening at the restaurant where he works alongside Jie, Steelhead spots Xiu-Xiu in the company of yakuza leader Eguchi (Masaya Kato). Heartbroken by the sight of his beloved with another man, Steelhead drowns his sorrows in a night filled with alcohol and debauchery alongside Jie. Upon sobering up, he resolves to secure legal citizenship in Japan by any means necessary. Teaming up with his fellow countrymen, Steelhead initiates a money laundering scheme, deliberately excluding Jie due to his genuine kindness. Their undertakings soon attract the ire of Taiwanese triad leader Gao ([Jack Kao]), who uncovers a fix on one of his pachinko machines and vows to exact punishment. When Jie gets caught in the act, he suffers grave consequences—Gao brutally disfigures him and amputates his hand in a vicious interrogation for information.
Fueled by rage, Steelhead devises a plan to infiltrate Gao's establishment to rescue Jie. However, while there, he stumbles upon a conspiracy involving the Togawa group, a rival faction plotting to eliminate Eguchi. Unbeknownst to Eguchi, who arrives unarmed, Steelhead leaps into action just as Gao is about to strike, severing Gao's arm with a machete in a bold act of bravery. Together, Steelhead and Eguchi evade danger, leading Steelhead to the Eguchi estate for recuperation, where he reconnects with Xiu-Xiu. Heartwarming revelations unfold as Steelhead learns of their daughter Ayako, now named Yuko, thriving within her new life. In gratitude for saving him, Eguchi offers Steelhead a lucrative position within the yakuza, which Steelhead promptly declines.
As time passes, Eguchi's attempts to expose the Togawa group's assassination plot fail miserably, culminating in him being forced to apologize. Desperate, Eguchi then approaches Steelhead, beseeching him to work as a hitman, to which Steelhead reluctantly agrees under the conditions that he'd take over Gao's territories and gain legal residency in Japan. Methodically eliminating his targets ignites a gang war within the yakuza, leading to Eguchi's ascension and Steelhead's integration into the violent ranks, now serving Eguchi as a vassal.
Determined to forge a better life for his Chinese companions, Steelhead shies away from yakuza activities, instead nurturing a successful tractor business. However, in 2006, Detective Kitano confronts Steelhead with a dire warning: his "brothers" are becoming entangled with yakuza drug trafficking, putting them all at risk of arrest. In a desperate bid for freedom, Steelhead and Kitano make a pact where Steelhead would gather evidence against Eguchi.
On the night of reckoning, Steelhead urges his comrades to abandon their perilous yakuza dealings, but they refuse, choosing the allure of wealth over safety. Chaos erupts as Eguchi arrives, and amidst the turmoil, Steelhead is betrayed and stabbed by those he thought were allies. Concurrently, factions within the yakuza grow restless, and a coup is underway against Eguchi, resulting in a violent confrontation leaving a trail of bodies.
As only Steelhead, Eguchi, and Kitano manage to escape the chaos, the cost of their betrayals and ambitions becomes grimly apparent. Mortally wounded, Eguchi hands Steelhead a flash drive containing incriminating data on yakuza operations—a final act of defiance. In a harrowing escape from the impending law enforcement, Steelhead bids a poignant farewell to a dying Jie, who did not survive the attack.
In a pivotal moment, Steelhead desperately calls Yuko to meet Ayako, only to find Togawa has taken Ayako hostage. In the ensuing conflict, Nakajima blocks Steelhead’s path, culminating in a desperate shootout where Steelhead is grievously wounded. However, as the police arrive, Nakajima meets his end, allowing Steelhead to flee.
Steelhead, now overwhelmed and caught in the unforgiving currents, sacrifices his chance at survival by entrusting Kitano with the flash drive, fulfilling his debt to the detective while reminiscing about the brighter times spent with his brothers, leaving behind a trail of shattered dreams and broken bonds.
