Three years after the events of Rush Hour 2, Chinese Ambassador Solon Han (Tzi Ma) discusses the crucial fight against the Triads at the World Criminal Court in Los Angeles, with Chief Inspector Lee (Jackie Chan) acting as his bodyguard. Just as Han prepares to reveal the location of the elusive Shy Shen, a significant figure for the Chinese mob, an assassin strikes, triggering chaos in the courtroom. Lee, in pursuit of the shooter, discovers that it is none other than his childhood foster brother, Kenji ([Hiroyuki Sanada]). In an unfortunate moment of hesitation, Lee allows Kenji to slip away as Detective James Carter ([Chris Tucker]) arrives on the scene after hearing the commotion over the police radio.
While Han survives this assassination attempt, Lee and Carter make a promise to his daughter, Soo Yung ([Zhang Jingchu]), to track down those responsible. Upon her insistence, they visit a local Kung Fu studio to collect an envelope that Han had entrusted her with, meant for Lee should anything happen. However, they soon find out that the Triads have stolen Soo Yung's possessions. Determined to protect her, Lee and Carter return to the hospital, where they intercept a group of French-speaking Chinese assassins before they can finish off Han. With the assistance of Sister Agnes ([Dana Ivey]), a French-speaking nun, they interrogate one of the captured gang members, who provides them with a name—Genevieve—and an address.
To ensure Soo Yung's safety, they place her in the care of the French ambassador, Varden Reynard ([Max Von Sydow]), at the French Embassy. However, their efforts are thwarted when an explosive car bomb nearly takes her life, compelling Lee and Carter to head to Paris, suspecting that the address they received leads to vital information. Upon their arrival, they find themselves in a seedy underground titty bar, further complicating their mission.
Their journey takes a wild turn as they encounter Commissaire Revi ([Roman Polanski]), who brutally interrogates them about the purpose of their visit while they insist they're simply on vacation. They also meet a disgruntled taxi driver, George ([Yvan Attal]), who begrudgingly agrees to drive them to the Triad hideout. During their escapade, Carter finds himself engaged with Geneviève ([Noémie Lenoir]) at a blackjack table while Lee faces deception from mob assassin Jasmine ([Youki Kudoh]). Just when Lee is cornered, Carter springs into action, allowing both to escape, albeit barely.
After a precarious hotel recuperation, Lee reveals the depth of his past with Kenji, explaining that they grew up in the same orphanage but ended up on drastically different paths. Lee’s resolve to confront Kenji becomes more profound when he learns from Reynard that Shy Shen is actually a list of the three Triad leaders known as dragon heads, and that Geneviève serves as Han's informant, possessing crucial information.
Upon rescuing Geneviève from yet another assassination attempt, they are determined to get to the bottom of this conspiracy, but betrayal awaits them. Upon reaching the embassy, they discover Reynard’s true colors as he attempts to sacrifice Geneviève. Kenji calls to inform Lee that Soo Yung has been captured and demands Geneviève in exchange.
Lee and Carter meticulously plan the meeting at the Eiffel Tower, with Carter disguising himself as Geneviève. Kenji challenges Lee to a sword fight, resulting in a tragic confrontation that ends with Kenji’s demise as he falls to his death. Meanwhile, as Carter fights to save Soo Yung, he engages Jasmine, who meets her end in a dramatic fashion.
As they fend off the remnants of the Triad forces, a final confrontation with Reynard arises. Just when things seem dire, George intervenes, shooting Reynard and ensuring their victory. As the police arrive on the scene, Revi attempts to steal credit for their success, but Lee and Carter swiftly take their leave, celebrating their hard-won triumph with a victory dance.
