A small-town seductress notifies her three best friends that she has run off with one of their husbands.

Just as they are about to board a boat for an all-day charity picnic, three married women of suburban New York--Deborah Bishop, Lora May Hollingsway and Rita Phipps-- receive a single letter from Addie Ross, the sophisticated town flirt, informing them that she has run off with one of their husbands. Although the women outwardly make light of Addie's cruel letter, which fails to name the errant husband, they are all deeply disturbed by its content. Deborah's businessman husband Brad has gone to the city and has told Deborah that he cannot attend their country club's first dinner dance of the season that night. George, Rita's husband, an erudite high school English teacher, has forsaken his usual Saturday morning fishing trip and donned a suit without telling his wife why, and Lora May's spouse Porter, the owner of a chain of department stores, has been spotted at the train station. During a free moment, Deborah thinks back on her young marriage: On the night of a previous opening dinner dance, newlywed Deborah, who along with Brad has just been discharged from the military, worries that she will not be accepted into Brad's circle of worldly hometown friends. Although Brad reassures her, the farm-reared Deborah frets about her unruly hair and unfashionable, pre-war mail-order party dress. By the time Rita and George arrive, Deborah is drunk and in a panic. Kindly Rita gives Deborah a pep talk and suggests that she cut the garish artificial flowers off her dress. While snipping, however, Deborah accidentally cuts a hole into the midriff of the dress and is forced to pin the flower back on. During the dinner dance, Deborah sits forlornly with Porter, who, though rough-hewn himself, complains about Lora May's lack of class. When champagne arrives courtesy of Addie, both Porter and Brad, who had been romantically linked to Addie prior to the war, express their admiration for her. Brad then insists that Deborah waltz with him, and Deborah is humiliated when the flower flies off her dress, exposing the tear and her bare midriff. Deborah runs to the bathroom, where Rita consoles her. Bolstered by Rita, Deborah returns to the dance, only to spot Brad outside, talking with Addie. Back at the picnic, Deborah comes out of her reverie and seeks out Rita. While trying to remain calm, Rita remembers her recent past: An overworked radio soap opera writer, Rita has invited her employers, advertising tycoons Mr. and Mrs. Manleigh, to dinner, hoping to sell them on an idea involving George. Unaware of his wife's plan, George criticizes Rita's desire to impress the Manleighs and refuses to don his tuxedo. Addie's birthday present for George, a phonograph recording of a Brahms piano concerto, then arrives, along with a quote from Twelfth Night , an amateur production of which they had co-starred in years before, and Rita is embarrassed to admit she had forgotten her husband's birthday. Moments after they sit down to eat, the Manleighs insist on interrupting the meal to listen to two radio dramas on which their company advertises. Afterward, Mrs. Manleigh cajoles George into critiquing the programs, and George happily expresses his total disdain for commercial radio. Insulted, Mrs. Manleigh informs Rita that her "little project" is off, and leaves. When George finds out that Rita had been hoping to secure him a high-paying story editing job with the Manleighs, he denounces her ambitions and reiterates his love of teaching. Rita concludes her recollections and then questions Lora May about her feelings. Although Lora May maintains that she is not concerned about Porter running off with Addie, she, too, becomes lost in thought, contemplating her past: As a young salesclerk, Lora May Finney lives with her mother and sister in a rundown house situated next to the railroad tracks. Although Porter is many years her senior and her boss, Lora May begins dating him, determined to secure a marriage proposal. When the divorced Porter resists her manipulations and tries to romance her with no strings attached, she turns him away. On New Year's Eve, Porter, who is infatuated with Lora May but is also attracted to Addie, comes to Lora May's house and begs to see her. Lora May stands firm, however, insisting that she will not resume their relationship without a commitment. Desperate, Porter proposes, but his lack of enthusiasm nevertheless depresses Lora May. In the present, the picnic concludes, and the three women head for home, each one wondering if she will find her husband. Rita's fears are immediately alleviated when she discovers George listening to his concerto. George explains to Rita that he had been asked to direct the school's production of Twelfth Night , but because of their fight over the Manleighs, never had a chance to tell her about it or his rehearsal that morning. Overjoyed, Rita announces that she is not working on weekends anymore, and will spend more time with her family. Deborah, meanwhile, arrives home to learn that Brad will not be coming home that night and assumes the worst. Lora May also finds Porter absent, but he returns home later that evening. During the country club dance, a depressed Deborah confides to Porter that Brad has run off with Addie. As his wife listens, Porter informs Deborah that he was the one who ran off with Addie, but that he changed his mind. After Deborah leaves, Porter reveals to the others that he confessed in order to relieve Deborah's anxiety. Expecting rejection, Porter then tells Lora May that she can use his admission to instigate lucrative divorce proceedings. Instead, Lora May lovingly calls her husband a "big gorilla," and they join George and Rita on the dance floor.