Based on the play by Brecht, it is the story of criminal leader Mack the Knife in London. His strong relationship with the chief of police allows his brutal crimes to go unpunished, until he upsets the powerful Peachum by marrying his daughter. Peachum profits by requiring all beggars in town to be licensed through him, and to pay him their earnings. The film explores the relations between organize crime, the police, finance, capitalists and the poor.