Franklin Maurice Hatchett (Chris Tucker) is a fast-talking small-time car wash hustler and ticket scalper who owes money to a local mobster named Carmine (Damian Chapa). The police are informed of his crimes by an investigating news reporter named James Russell (Charlie Sheen) after Hatchett unintentionally thwarts Russell’s attempts to have him confess his crimes on camera, and he is arrested. When placed on a prison transport unit, he is handcuffed to a French criminal named Raymond Villard (Gerard Ismael). The transport unit is attacked on a bridge with mercenaries killing all the police officers and prisoners except for Franklin and Villard; the mercenaries are Villard’s men. Because he is handcuffed to Franklin he decides to bring him along, and they escape on a helicopter with another French criminal named Dubray (Frank Bruynbroek). While on the helicopter, Franklin overhears the two discussing the location of a cache of stolen diamonds. Franklin then jumps out of the helicopter after realizing that Villard and Dubray plan to kill him. Franklin is recognized by police officers but is able to elude them, and he decides to call Russell after seeing his face on an advertisement.
Russell has just been fired from his job at Channel 12 News after arguing with his manager, but he convinces Franklin to hide with him because the next week is Sweeps Week. He arranges to get his job back with an exclusive interview of Franklin. Together they attend Russell’s wedding rehearsal dinner, where Franklin meets Russell’s fiancé Grace (Heather Locklear) and ingratiates himself to Grace’s father (Paul Sorvino) by pretending to be Vic Damone’s son. In the meantime, two police detectives question Franklin’s girlfriend Paula (Elise Neal) and wiretap her phone. After calling Paula, Franklin tries to leave but realizes that the police are searching for him, and he convinces Russell to help him. The two rampage all over the city to find clues to clear Franklin’s name, including calling a bomb threat on a European nightclub, getting shot at by the police when they visit Paula, and being chased by Villard and Dubray, who murder a shopkeeper in the process, which eventually gets Russell’s name involved and spread all over the news. The two visit Franklin’s childhood friend Aaron (Michael Wright), a local arms dealer, who gives them guns and promises to help if they get into trouble. The following morning, Franklin convinces Grace’s father to take him to the auto expo where the Europeans stashed the diamonds (in a Jaguar XK140). Franklin and Grace’s father get into a bidding war with Villard and Dubray over the car with the diamonds inside, which ends with Dubray chaotically chasing Franklin across the city while Villard kidnaps Russell.
Villard then calls Franklin using Russell’s phone, and demands the return of his diamonds. Realizing that he has no chance on his own, Franklin calls the police detectives, Carmine, the French mercenaries, and Aaron, telling them all to meet him at the Los Angeles Memorial Coliseum. It is revealed that one of the detectives (Paul Gleason) is a dirty cop working for Villard. A massive shootout ensues in which both police detectives and Carmine and his crew are all wiped out. Aaron shows up with a henchman, an assault rifle, and an RPG, and proceeds to wipe out most of Villard’s men, including Dubray. In the meantime, Russell manages to escape from Villard’s men, after placing several un-pinned grenades beneath his helicopter, ready to detonate if he tries to take off. He then reunites with Franklin, saving him from being shot by Villard. However, when cornered once again, Franklin realizes that the diamonds are not worth dying for, and throws them at Villard’s remaining men, who drop their weapons and begin grabbing as many as they can. The police arrive in the meantime. Villard tries to escape in the helicopter and the grenades detonate, killing him. In the end both Franklin and Russell are cleared and branded as heroes. Franklin saves an unknown amount of the diamonds and puts one on a wedding ring that he gives to Russell, who marries Grace with Franklin as his best man.