After the events of Rush Hour, LAPD Detective James Carter is in Hong Kong visiting his friend, Hong Kong Police Force Chief Inspector Lee. Their vacation is put on hold when a bomb at the United States Consulate General kills two undercover U.S. Customs agents. Lee is assigned to the case and discovers that his late father's police partner, Ricky Tan, is somehow involved. Lee and Carter attempt to question Ricky, now a leader of the Triads, resulting in a brawl with his bodyguards.
The U.S. Secret Service, led by Agent Sterling, and the Hong Kong Police Force fight over jurisdiction of the case. Lee's office is bombed and Lee, unaware Carter has left the building, believes him dead. They cross paths at a party on Ricky's yacht, where Ricky scolds his underling, Hu Li. Lee and Carter confront Ricky, who claims he is being framed by his enemies and asks for protection, but Hu Li shoots him and escapes. Sterling holds Lee responsible for Ricky's death and orders him off the case. Carter is ordered back to Los Angeles, but convinces Lee to return to LA with him.
Carter assures Lee that every large criminal operation has a rich white man behind it; in this case, he believes that man is Steven Reign, a billionaire Los Angeles hotelier he saw acting suspiciously at Ricky Tan's party. Staking out Reign Towers, they spot Isabella Molina, whom Carter met on Ricky's yacht, receiving a delivery from Hu Li. Mistaking the package for another bomb, Lee and Carter try to intervene, but Molina reveals she is an undercover U.S. Secret Service agent, looking into Reign's laundering of $100 million in superdollars.
Lee and Carter visit Kenny, an ex-con who runs a gambling den in the back of his Chinese restaurant. He tells them about a customer with a suspicious amount of hundred-dollar bills, which Carter confirms are Reign's counterfeits. They trace the money to a bank, where they are captured by Hu Li. Taken to Las Vegas in a Triad truck, Lee and Carter escape, realizing that Reign is laundering the $100 million through his new Red Dragon Casino.
At the Red Dragon, Molina points Lee to the engraving plates used to print the counterfeit money, while Carter creates a distraction to help Lee sneak past the security. Hu Li captures Lee, taping an explosive in his mouth before bringing him to Ricky, who faked his death. When Ricky departs, Molina tries to arrest Hu Li but is shot, and Lee removes the explosive before it detonates, evacuating the casino.
Carter fights Hu Li, accidentally knocking her out, while Lee pursues Ricky. In the penthouse, Reign prepares to escape with the plates but Ricky fatally stabs him. Lee and Carter confront Ricky, who admits to killing Lee's father. In the ensuing scuffle, Ricky falls to his death when Lee kicks him out of the window. Hu Li enters with a time bomb, forcing Lee and Carter to escape on a makeshift zip line as Hu Li dies in the explosion.
Later at the airport, Molina thanks Lee for his work on the case, and kisses him. Planning to go their separate ways, Lee and Carter change their minds when Carter reveals the large amount of money he won at the casino, and the pair head to New York City to indulge themselves.
