It is the mid-1920s, in Chicago Illinois. Velma Kelly, who, with her sister, performed a famous and popular double-act (until Velma is arrested for the murder of her sister and husband, who she found in bed together) welcomes the audience to the show (“All That Jazz”). Meanwhile, vaudeville wannabe Roxie Hart has sex with her lover, Fred Casely, who has not kept his word about introducing Roxie to a nightclub producer. In fury, Roxie shoots Fred dead.
When Roxie’s husband, Amos, returns home, she convinces him that Fred was an intruder whom she killed in self-defense, and begs Amos to take the blame. When Sergeant Fogarty arrives and begins the interrogation, Amos gamely does so (“Funny Honey”) until Fogarty shows him that Fred was no burglar at all -- in fact, Roxie was two-timing him. Upon Amos’ reversal, Fogarty arrests Roxie and takes her to the Cook County Jail.
At the jail, Roxie is introduced to the six “merry murderesses” of the Cook County Jail -- June, Annie, Liz,