The film is set in the 1930s. At an illegal card game, a young Street children witnesses the massacre of a group of mobsters at the hands of Flattop and Itchy, two of the hoods on the payroll of Alphonse "Big Boy" Caprice. Big Boy's crime syndicate is aggressively taking over small businesses in the city. Detective Dick Tracy catches the urchin (who calls himself "Kid") in an act of petty theft. After rescuing him from a ruthless host, Tracy temporarily adopts him with the help of his girlfriend, Tess Trueheart.