Answer:
The music in Chicago (2002) is key for the film, not only because it is a musical, but because it presents the life of vaudevillians during the Jazz Age.
Step-by-step explanation:
In Rob Marschall's Chicago (2002) is based on a Broadway crime-musical created in the 1970's, which in turn was inspired by a 1926 play by Maurine Watkins.
The musical acts in the theatre are staged following the classical vaudeville acts of the 1920's. In the film, mosts of this acts are presented as if they where in the mind of one of the main characters, Roxie Hart, a housewife who madly desires to become a performer as the other main character Vellma.