On the eve of Britain's handover of Hong Kong, Detective Inspector Lee (Jackie Chan) retrieves a valuable haul of art treasures from the villainous Sang (Ken Leung), henchman of crime boss Juntao. Two months later, Lee is called to Los Angeles when Sang kidnaps the daughter of Lee's friend, Han (Tzi Ma). The FBI, angered by Lee's involvement in what they see as their case, insist that he is partnered with their own disgraced detective, the unorthodox James Carter (Chris Tucker). Lee and Carter immediately clash, but the two men gradually develop a grudging respect for each other as they follow a series of clues to Sang's whereabouts.