CAN-CAN is a songfest about Paris in 1893 and some of its more Bohemian citizens. Aristide Forestier, a young, newly-appointed and over-zealous magistrate, decides to undertake a reform movement. The first case before him is a charge against some young women that their dance, the cancan, has violated the Paris morals code. Acting with the unique wisdom of the French, the chief judge dismisses the case because all of the witnesses seem suddenly to have had cinders in their eyes when the crime was committed and so cannot testify. Aristide goes to Montmartre to investigate the matter personally.