The story revolves around the life of C.C. Baxter (played by Jack Lemmon), a middle-aged man who lends his luxurious New York City apartment to his bosses (played by Fred MacMurray and Jack Warden) for their extramarital affairs. In return, C.C. gets to use the apartment to impress his own love interests. However, things take a complicated turn when C.C. falls for Fran Kubelik (played by Shirley MacLaine), the elevator operator in one of the buildings.