Marjorie Morgenstern (Natalie Wood) is an 18-year-old, middle-class, Jewish girl from New York who wants nothing more than to be an actress, despite the hopes and wishes of her parents (Everett Sloane and Claire Trevor) that she graduate from college, marry, and settle down to have a family. At the urging of her more worldly friend Marsha Zelenko (Carolyn Jones), she takes a job at an upstate camp, and, one night when sneaking onto the grounds of a neighboring resort, meets and falls wildly in love with the entertainment director, Noel Airman (Gene Kelly). A Lothario with a gift of song as well as dance, Airman romances Marjorie and tries to teach her something of theater, suggesting that she change her name to Marjorie Morningstar, which she does. He intends to enjoy her company for the summer, until her aging uncle Samson (Ed Wynn), who is also working at the resort, tells him of the family's concerns for the girl. Noel and Marjorie end up linked romantically, despite their best efforts to stay away from each other. Marjorie gives up a potential romance with a slightly older, successful doctor (Martin Balsam) and resists the honest entreaties of Airman's assistant, Wally Wronken (Martin Milner), and tries to get Airman to straighten up and fly right; she can't get her own acting career off the ground, but she owns Airman's heart. Instead of biding his time at writing a musical that he's been working at for four years, and spending his summers working in the Catskills, Noel tries to work in the advertising world -- he also finds himself just as troubled by the stable family life and religious life that Marjorie comes from as he is attracted to her personally. He is also bitterly disturbed by the fact that his one-time assistant Wally Wronken is now a successful Broadway playwright, the darling of critics and audiences, with backers eager to sign checks to produce his work. Unable to pursue a life in business, or remain faithful to Marjorie, he reaches a crisis point from which only she can rescue him -- together they try to build a life and he tries to finish his long-gestating masterpiece, which proves a disaster when it gets to Broadway. Noel abandons Marjorie, and when she goes to find him, Wally warns her off, explaining that Noel has to return to a place where he can feel successful, like the Catskills resort where they met, where he can be the big fish in the tiny pond. Her marriage over and her girlish ideals behind her, she sees Noel back in his element, wowing young acting students with his skills, and finally turns to the one man who has loved her for precisely who she is all along, Wally.