After successfully stealing an 86-carat diamond during a heist in Antwerp, Frankie "Four-Fingers" (Benicio Del Toro) makes his way to London to deliver the precious gemstone to diamond dealer Doug "The Head" (Mike Reid) on behalf of New York jeweler Cousin Avi (Dennis Farina), who financed the theft. Before proceeding, one of Frankie's accomplices advises him to visit his brother, the ex-KGB agent Boris "The Blade" (Rade Serbedzija), a notorious arms dealer, to acquire a weapon. Unbeknownst to Frankie, the brothers have ulterior motives and plan to rob him using a third party to obscure their involvement.
Simultaneously, Turkish (Jason Statham), an unlicensed boxing promoter and casino owner, persuades local gangster Brick Top ([Alan Ford])—the head of a ruthless unlicensed boxing and dog-fighting circuit—to include matches from his fighter Gorgeous George ([Adam Fogerty]) in Brick Top's betting operations. However, things take an unexpected turn when George gets into an unsanctioned boxing match against Mickey O'Neil (Brad Pitt), the bare-knuckle boxing champion. Mickey’s incredible prowess leaves George severely injured after a single punch. With no other options, Turkish agrees to recruit Mickey for an upcoming match, promising to buy a new caravan for Mickey’s mother ([Sorcha Cusack]) as a form of compensation.
In an ironic twist, Brick Top consents to the change in fighters but demands that Mickey deliberately loses in the fourth round. As these events unfold, Boris provides Frankie with a firearm in exchange for a favor: Frankie is to place a bet on Boris’ behalf at Brick Top’s establishment, since Boris owes money there and cannot make the trip himself. Avi, learning of this arrangement, immediately travels to London accompanied by his bodyguard Rosebud ([Sam Douglas]) to reclaim the diamond.
Things get chaotic when Boris employs two pawnbrokers, Vinnie ([Robbie Gee]) and Sol ([Lennie James]), to rob Frankie of the diamond while he is at the bookmakers. The useless robbery spirals into comedic misadventures when Frankie is inadvertently kidnapped on camera. Instead of complying with Brick Top's orders to lose the fight, Mickey knocks George out in a shocking display, leading to heavy monetary losses for Brick Top’s financiers. Enraged, Brick Top retaliates by robbing Turkish of his finances and demands that Mickey fight again, this time ensuring he loses.
As Boris successfully retrieves the diamond, he also eliminates Frankie, leaving Sol, Vinnie, and their driver Tyrone ([Ade]) to figure out how to dispose of the body. They become trapped in their own predicament when Brick Top arrives, outlining his gruesome preferred method of body disposal: feeding bodies to pigs. In a desperate measure, Sol attempts to bargain for their survival by offering Brick Top the stolen diamond, resulting in a tense countdown to retrieve it within 48 hours.
Meanwhile, Avi and Doug hire the fearless mercenary Bullet-Tooth Tony ([Vinnie Jones]) to track down Frankie. The search leads them to Boris, who they capture to reclaim the diamond, all while pursued by Sol, Vinnie, and Tyrone. As the pursuits intensify, a series of unfortunate accidents ensue, culminating in the death of Rosebud and the escape of Boris. A confrontation ensues at a pub, where Tony deftly handles a fragile situation with the bumbling pawnbrokers.
Amidst the frantic chase, Boris is eventually killed by Tony, but Sol and Vinnie elude capture with the diamond tucked away in Vinnie's pants. Their luck runs out when they attempt to produce the diamond at their pawn shop, only to watch in horror as it gets swallowed by a dog that Vinnie had acquired from the Pikeys. In a wild twist of fate, Avi mistakenly shoots Tony while attempting to recover his lost treasure, ultimately giving up on the chase and returning to New York.
As tensions rise again, Mickey leverages his situation, refusing to fight unless Turkish acquires a more lavish caravan for his mother. A series of ever-escalating actions result in Brick Top's goons vandalizing Turkish's gambling establishment and escalating their threat to Mickey's family. Faced with no choice, Mickey reluctantly agrees to fight, even as a night of drinking threatens to derail him. Despite a brutal beatdown, Mickey manages to persist to the fourth round, where he scores a shocking knockout, turning the tables on Brick Top by orchestrating an ambush with his allies.
In the aftermath, Turkish and Tommy discover the Pikey campsite vacated and are faced with police interrogation. They fabricate a story about walking Vinnie’s dog, which serendipitously returns with the diamond nestled in its stomach. They consult Doug for guidance on selling the gem, leading to the inevitable return of Avi to London, setting the stage for more mayhem centered around the diamond and the intersecting lives embroiled in this chaotic world.
