Eight men eat breakfast at a Los Angeles diner before carrying out a diamond heist. Mob boss Joe Cabot and his son and underboss "Nice Guy" Eddie Cabot are responsible for planning the job. The rest of the men use aliases issued by Joe Cabot: Mr. Brown, Mr. White, Mr. Blonde, Mr. Blue, Mr. Orange and Mr. Pink.
After the heist, White flees with Orange, who was shot during the escape and is bleeding severely in the back of White's car. At one of Joe's warehouses, White and Orange rendezvous with Pink, who believes that the job was a setup, and that the police were waiting for them. White informs him that Brown is dead, Blue and Blonde are missing, and Blonde murdered several civilians during the heist; White is furious that Joe, his old friend, would employ Blonde, whom he describes as a psychopath. Pink has hidden the diamonds nearby. He argues with White over whether or not they should get medical attention for Orange, and the pair end up having a fight and draw guns at each other. They stand down when Blonde arrives with a kidnapped policeman, Marvin Nash.
Some time earlier, Blonde meets with the Cabots, having completed a four-year jail sentence. To reward him for not having given Joe's name to the authorities for a lighter sentence, they offer him a no-show job. Blonde insists that he wants to get back to "real work," and they recruit him for the heist. In the present, White and Pink beat Nash for information. Eddie arrives and orders them to retrieve the diamonds and ditch the getaway vehicles, leaving Blonde in charge of Nash and Orange. Nash denies knowledge, but Blonde ignores him and resumes the torture, cutting off Nash's ear with a straight razor. He subsequently prepares to set him on fire, but Orange shoots him dead. Orange then reveals to Nash that he is an undercover police officer, and that the police will arrive soon.
The story now flashes back to Orange - real name Freddy - and his infiltration into the crew of thieves. The story follows him as he uses an elaborate tale of a drug delivery to gain acceptance and befriends Mr. White, who takes Orange under his wing as the veteran thief. It is revealed that Orange was shot in the gut, not by a police officer, but by a civilian woman during a carjacking as Orange and White fled the failed heist.
When Eddie, Pink, and White return, Orange tries to convince them that Blonde planned to kill them all and steal the diamonds for himself. Eddie impulsively kills Nash and accuses Orange of lying, since Blonde was loyal to his father. Joe arrives with news that the police have killed Blue. He is about to execute Orange, whom he suspects is the traitor behind the setup, but White intervenes and holds Joe at gunpoint, asserting wrongly that Orange is not an undercover cop. Eddie promptly aims at White, creating a Mexican standoff. All three fire; both Cabots are killed, and White and Orange are hit.
Pink, the only uninjured person, takes the diamonds and flees. As White cradles the dying Orange in his arms, Pink can be heard being arrested by the police, and Orange confesses that he is an undercover officer; White sobs and presses his gun to Orange's head. The police storm the warehouse and order White to drop his gun. Gunshots sound, and White collapses.