In 19th century London, Macheath — known as Mackie Messer ("Mack the Knife") — is a Soho crime lord whose former lover is Jenny, a prostitute in a brothel on Turnbridge Street.

The celebration is attended by Jackie “Tiger” Brown, Mackie's old comrade-in-arms from their army days in India who is now Chief of Police and about to oversee a procession through the city for the queen’s coronation.

Polly's father, Mr Peachum, who runs a protection racket for the city's beggars, outfitting each with an appropriate costume, is furious at losing his daughter to a rival criminal.

Tipped off by Brown to lie low, Mackie goes to the brothel, where the jealous Jenny betrays his presence to Mrs Peachum and the police.

Peachum tries to stop the protest march at the last minute but fails, and the procession escalates into a battle between beggars and police, enraging the new queen.

Peachum and Brown, whose careers are both ruined by the beggar demonstration, also come to the bank and agree to join forces with Mackie.

Brecht and Weill intended the piece as a satire on capitalism, and claimed that the ideological basis of the story was softened by director G. W. Pabst, who wanted the film to be more entertaining.