A diamond of prodigious size is stolen from Antwerp by an American thief. En route back to New York, he takes a slight detour in London, at the suggestion of a treacherous partner, who sets the thief (Franky Four Fingers) up with his cousin, Boris. Boris hires incompetent thieves to retrieve the diamond from a bookies, where FFF went to place a bet. The bookies belongs to Brick Top, a local underworld kingpin who runs illegal fights. In his fights, a fighter is being staged by two boxing promoters, Turkish and his partner Tommy. Turkish decides to improve his office a little bit, and sends Tommy to a gypsy campsite to buy a caravan. The boxer, Gorgeous George, is knocked out at the campsite, and Turkish decides to replace the boxer with Mickey, the gypsy leader. After Brick Top's bookies are robbed, Boris double-crosses the two incompetents, and kills FFF. Franky's boss comes to London for the sake of the diamond, and this is the final event which sets off a chain of events and characters involving wild gypsies, phenomenally stupid thugs, hapless boxing promoters, immortal Russian arms dealers and... a stray dog.