On the eve of Winsocki Military Institute's senior prom, graduating cadet Elwood C. "Bud" Hooper is in a conundrum because movie star Lucille Ball has unexpectedly accepted his prom invitation, but he has already submitted his girl friend Helen Schlessenger's name to the graduation review committee. Although Bud has told Helen that he is too sick to attend the prom, he is unsure what to do with Lucille, as it is too late to submit another name. Bud's cadet friends, Dutch Miller and Harvey "Hunk" Hoyt, convince Bud to take Lucille under Helen's name, unaware that Lucille's sole purpose in coming to Winsocki is to gain some much-needed publicity for her sagging career. Soon after Lucille and her agent, Jack O'Riley, check into their hotel, bumbling photographer Chester Short of the Philadelphia Bugle arrives, having been summoned by Jack. Jack's plan to get a photo of Lucille and Bud together backfires when Helen shows up, furious because she has heard that Bud is not sick, but is taking another woman to the prom. Seeing Bud's obvious distress and Helen's jealousy, Lucille asks Jack to call off the stunt, but Jack assures her that everything will work out. At the prom, as a depressed Helen mopes about the ladies' waiting room, Bud slips in, anxious to apologize. Helen gladly accepts the apology until Bud asks her to allow Lucille to go to the dance in her stead. Her jealousy reignited, Helen throws Bud out of the waiting room, after which Dutch and Hunk, whose own dates are unaware of their involvement with Lucille, escort the actress to the chaperoned dance. Much to Lucille's dismay, Dutch and Hunk, who are anxious to have her to themselves, insist on dancing with her in dark corners. Jack, meanwhile, is forced to sneak in to the prom disguised as a waiter, then is chased off by the ever-vigilant Captain Bradd. When homely blind date Nancy is accidentally given Lucille's fur stole by the hat check boy, the movie star's presence is suddenly made known. Just as a disgruntled Lucille is about to leave, Jack convinces Bud that Lucille is worried about him, and he agrees to ask her to dance the traditional "ring" waltz with him. Believing that she is doing him a favor, Lucille accepts his invitation and is publicly introduced as Helen during the formal dance. Upon hearing her name called, Helen storms into the dance hall and confronts Lucille, angrily ripping a flower from her gown. The starstruck cadets then descend on the actress and tear her clothes to shreds for souvenirs. Chester captures the riotous moment on film, and a half-dressed Lucille runs from the hall screaming. Bud hides Lucille in his dorm room closet, and she is soon joined by Jack, Chester, Helen and Nancy. When an angry Bradd comes looking for Lucille, Bud manages to allay his suspicious for a while, but Bradd eventually discovers the interlopers. The next day, Lucille is annoyed to see a titillating photo of her and the cadets in the Bugle and denounces Jack. Just then, Bud shows up at her hotel to say goodbye and lies that he has straightened everything out with Bradd and Helen. After Bud leaves, Helen arrives and tells Lucille that Bud will not be graduating that day. Feeling responsible for Bud's plight, Lucille decides to plead his case to Major Roger W. Reeber. Although sympathetic, Reeber reveals that Bud's military future is in the hands of the school's board of officers, which is headed by Colonel Harkrider. Lucille charms Reeber into bringing the matter up to the board and coaches him on how to make the dress incident sound like all-American fun. Lucille's ploy works, and while she watches the proceedings with a starstruck Colonel Harkrider, Bud graduates and is embraced by a forgiving Helen.