Detective Marcus Burnett (Martin Lawrence) and Detective Mike Lowrey (Will Smith) are officers in the Miami Police Department. While Lowrey is from a wealthy background and enjoys a playboy-like lifestyle, Burnett is married with three kids. One night, $100 million of seized heroin is stolen by gangsters from a secure police vault. This was a major blow to Burnett and Lowrey, because it was the biggest drug bust of their careers. Now they are faced with an ultimatum from Internal Affairs?if they do not get the drugs back in five days, the narcotics division will be shut down. In the course of the investigation, it is discovered that one of the gang members, Eddie Dom?nguez, has absconded with some of the heroin. Dominguez is shot to death by a French drug kingpin by the name of Fouchet (Tch?ky Karyo), who also kills escort girl Max, one of Lowrey's ex-girlfriends. The only witness to the crime is Max' roommate Julie Mott (T?a Leoni). Julie will only testify to Lowrey, who is temporarily absent, so Burnett is forced to impersonate him in order to get her to co-operate. In order to continue the deception Burnett moves Julie into Lowrey's apartment, where he himself has to move into while Lowrey moves in with Burnett's family and claims to be Burnett in Julie's presence while Burnett claims to be Lowrey. Meanwhile, Fouchet and his gang of criminals kidnapped Julie. Burnett, Lowrey and the Miami P.D. organize a team of commandos to stop the criminals from killing Julie and selling the drugs to a Colombian drug lord. A final battle erupts between Burnett, Lowrey and the criminals. The criminals are eliminated, Julie is saved in the process and Lowrey kills Fouchet.