All is status quo at the Linnett household: The boys come calling on Joy (Janis Paige), Jackie (Joyce Reynolds) tends to her studies, and each parent (Edward Arnold and Barbara Brown) frets about their biological child. The sand in the oil arrives in the form of an old acquaintance, Warren James (Robert Hutton), who has matured somewhat since the stepsisters last saw him. Jackie is overjoyed when Warren first falls for her and asks her to the country-club dance, but all her romantic dreams fly out the window once Warren gets gobsmocked by the sight of Joy in a swimsuit. Sick of being beaten out, Jackie decides to join Joy on the flirty side of things, and undergoes a makeover with surprising results.