Shirley MacLaine in Irma la Douce (1963)

Naive, by-the-book French police officer Nestor Patou, is transferred to the Red Light district. Upon witnessing what must be a brothel, he calls the station, organizes a raid, and transports all the ‘ladies’ to the jail. Unfortunately, this disrupts the well-organized system of the police and the Pimps union. Not to mention inadvertently netting his station superior at the brothel. Fired, he goes to a bar to drink, is befriended by Irma, beats up her pimp, and finds he is that he is her pimp now. He does not like the thought of his girl seeing other men, so he comes up with a plan.