James Carter (CHRIS TUCKER) is an LAPD detective who's on vacation in Hong Kong visiting his friend, Detective Inspector Lee (JACKIE CHAN), with whom he previously solved a kidnapping case and who's now too busy working to relax. That doesn't let up when a mysterious woman, Hu Li (ZHANG ZIYI), drops off a package - that turns out to be a bomb -- at the American embassy and it ends up killing two U.S. Customs agents.
They were working on a major counterfeiting ring that's been producing and distributing nearly undetectable "super bills" in one-hundred-dollar denominations. While the Hong Kong police believe that Chinese triad ruler Ricky Tan (JOHN LONE) is responsible, Secret Service special agent Sterling (HARRIS YULIN) thinks it's even bigger than him, and wants neither Lee nor Carter working on the case.
Lee ignores that, however, since Tan was his father's ex-partner who turned bad and murdered the cop. Soon he and Carter are on the case, applying their distinctive methods of investigation into solving it. When it appears that Hu Li has shot and killed Tan, however, Sterling orders Carter back to the States.
Carter convinces Lee to join him since he believes that Steven Reign (ALAN KING), a wealthy Los Angeles businessman, is somehow involved, and this leads to encounters with various people who may or may not be involved in the counterfeit ring. They include Isabella Molina (ROSELYN SANCHEZ), a woman who claims to be an agent working the case from the inside, as well as Kenny (DON CHEADLE), Carter's informant.
As Lee and Carter dig deeper and uncover more facts, they must contend with various attempts on their lives as they try to crack the case and nab all of the criminals.