Paris? the red-light district. A rookie police officer, Nestor Patou (Jack Lemmon), falls for a beautiful prostitute, Irma la Douce (Shirley MacLaine). Before long, Nestor discovers that the only way to keep Irma is to become her new pimp, and the only way to accomplish that is to knock the block off the present pimp. As a result, Nestor becomes #1 pimp on the block. It is not long, though, before he becomes insanely jealous of Irma's customers. Despairing, Nestor devises a way to keep Irma all for himself, yet allow her to continue in her profession. And when the plan backfires, there is only one person who can help him... but will she believe him? Lemmon's comic performance, under the direction of Billy Wilder, has been compared to some of the great visual comedy of the silent comedians.