Franky Four Fingers (BENICIO DEL TORO) is a diamond thief with a gambling problem who's just heisted an 84-carat stone in Antwerp for his boss, Avi (DENNIS FARINA), who's back in New York.
Franky's supposed to deliver the diamond to Avi's jeweler cousin, Doug the Head (MIKE REID), in London, but Russian criminal Boris the Blade (RADE SHERBEDGIA) convinces him to place a bet on an illegal boxing match instead.
He does so because he's hired pawnshop owners Vinny (ROBBIE GEE) and Sol (LENNIE JAMES) and their overweight getaway driver, Tyrone (ADE), to rob Franky. Despite what seems like a foolproof plan, things go wrong, which can also be said about the endeavor begun by Turkish (JASON STATHAM) and his business partner Tommy (STEPHEN GRAHAM).
They've recently gotten into the unlicensed boxing business and have scheduled a fight with another boxing promoter, Brick Top (ALAN FORD), a notorious criminal kingpin who feeds his victims to the swine at his local pig farm. When a local gypsy, Mickey O'Neil (BRAD PITT), knocks out their contender, Gorgeous George (ADAM FOGERTY), in a street fight, the two suddenly find themselves in deep water since they no longer have a fighter to take a dive in the fourth round against Brick Top's competitor.
Things get worse when they convince Mickey to take Gorgeous George's place and he knocks out his opponent instead of taking that dive. Brick Top is furious, but agrees not to kill the two novice promoters if they can get Mickey to fight again, but get it right this time. Meanwhile, and having heard that Franky's missing, Avi boards a plane and heads for London, where he hires the seemingly unstoppable
Bullet Tooth Tony (VINNIE JONES) to find Franky and retrieve the stone.
From that point on, the various paths of all those players crisscross as the preparation for the next boxing match and the hunt for the missing diamond set into motion a series of zany and chaotic events that end with plenty of violence.