A teenage girl's crush on a playboy spells trouble, particularly when he falls for her older sister.

After Margaret Turner, an attractive, single judge, hears a case involving Dickie Nugent, a playboy artist on trial with three acquaintances for brawling in a Los Angeles nightclub, she issues a warning and dismisses the defendants. Later that day, Dickie delivers a lecture on art at a local high school, and Margaret's teenage sister and ward Susan, who is in attendance, becomes infatuated with him. Inspired by a vision she has of Dickie as a knight in shining armor, Susan insists on interviewing him for the school paper. To satisfy Susan's over-eager curiosity, Dickie invents a lurid past for himself and agrees offhandedly to use her as a model for one of his "Americana" paintings. That night, Susan reveals her infatuation to a disapproving Margaret and, after sneaking away from home, wangles her way into Dickie's empty apartment. Susan falls asleep while waiting for Dickie, causing Margaret and her boyfriend, Assistant District Attorney Tommy Chamberlain, to panic with worry. Just as Margaret deduces where Susan has gone, Dickie returns home and finds the teenager half-asleep on his couch. Margaret and Tommy burst in on the couple, and by the next morning, Dickie is in jail, having been arrested for, among other things, slugging Tommy. While in his cell, Dickie is visited by court psychiatrist Dr. Matt Beemish, who is also Margaret and Susan's uncle. Sensing Dickie's innocence, Matt convinces Margaret, Tommy and the judge who is hearing Dickie's case to drop all charges on condition that Dickie agree to "date" Susan as a way of curing her of her infatuation. As mandated, Dickie escorts Susan to a high school basketball game, where her boyfriend, player Jerry White, becomes distracted with jealousy. Although Dickie tries to push Jerry back into Susan's arms by inviting them for a post-game soda, Jerry declares that he is resigned to losing Susan and offers to be her friend. After a frustrated Dickie says goodnight to Susan, he attempts a sincere flirtation with the serious-minded Margaret, but is awkwardly rebuffed by her. That weekend, Dickie accompanies Susan, Margaret, Tommy, Matt and Susan's other uncle, Judge Thaddeus Turner, on a neighborhood picnic. At Susan's urging, Dickie participates in several races, but loses them all in humiliating fashion to the smug Tommy. Desperate to prove his manhood, Dickie enters the big obstacle race, and because Jerry and Susan have bribed their teenage friends to perform badly and sabotage other entrants in the competition, Dickie beats Tommy and wins. As Dickie accepts his trophy, the now smitten Margaret envisions him as a knight in shining armor, just as her sister had before, and calls him that night for a date. Though exhausted, Dickie eagerly agrees to meet her at the Tick Tock Club, then to confuse Tommy, who has come to confront him, "confesses" that he is madly in love with Susan. Margaret and Dickie's romantic evening at the Tick Tock is shortlived, however, as Susan, Tommy, Jerry and Joey and Agnes Prescott, two of the co-defendants from Dickie's court appearance, join them at their table. While Susan denounces Margaret for "stealing" Dickie, Jerry becomes angry at Susan for not caring about his recent draft notification. A jealous Tommy then accuses Dickie of immoral conduct, and as the rest of group argues noisily, Agnes screams that Dickie has ruined her birthday. After Susan and Margaret storm home, Matt uses his psychological skills to convince the younger sister that she is not in love with Dickie. Susan apologizes to Margaret, who then is persuaded by Matt to fly away for a short vacation to "forget" Dickie. Unknown to Margaret, however, Matt has spoken to an equally depressed Dickie and knows that he is planning to fly out the next day. At the airport, Matt tricks the police into preventing Tommy from arresting Dickie by telling them that Tommy is a mental patient who believes he is the district attorney, and brings the reluctant lovers together at last.