Chantal Stacy [Sandra Dee] is a very cute girl, the daughter of Germaine Stacy [Micheline Presle], a former French showgirl, and John Stacy [John Lund], a conservative Boston antiques dealer who met in Paris. Their lighthearted “soufflé-and-beans romance” paints her world with a blend of Parisian charm and New England pragmatism, and a foghorn sounds every time a man gets too close to her, signaling her father’s wary guard over her French-side temptations.
The family relocates to New York City after John gets a promotion, bringing Chantal into a bustling new life. On Fifth Avenue, she’s spotted by Eugene Wright [Bobby Darin], a photographer who invites her to model. During Chantal’s first shoot, her father storms onto the set, punches Gene, and whisks his daughter home. Chantal confesses to her mother that she enjoys modeling and would like to continue, but with her mother’s guidance she agrees to marry Gene. Yet once married, Gene refuses to let Chantal model, turning her into a housewife instead.
Shortly after, Chantal’s college friend Tina [Stefanie Powers], a spoiled, pampered New York socialite, arrives and begins flirting with Gene, drawing his attention away from Chantal and making her increasingly anxious about her marriage. When Chantal feels lost, her mother lends a hand with some old-fashioned advice and a book titled How To Train Man’s Best Friend. The idea is explained not as a way to dominate a husband, but as a guide to living with him—an insight that slowly reshapes how Chantal approaches her relationship.
Tina’s drunken confession of loneliness and envy prompts Germaine to reveal another tactic she once used: taking a lover. She explains that her lover, Robert Swan, was only imaginary—yet she kept up the act by sending herself flowers and arranging prank calls, hoping to spark jealousy in her husband. The ruse is supported as the girls tease John about their accounts, blurring the line between fiction and reality. Before Chantal heads home to test these techniques, her mother warns that when Gene confronts her, she should answer honestly, lest he wonder if she’s telling the truth about an affair.
The plan seems to work as Chantal begins sending two-dozen white roses and has her mother click the receiver so Gene thinks there’s a mysterious caller. Gene, eager to uncover the truth, tracks down the florist to locate Robert Swan. Chantal rushes to explain everything, but Gene pleads with her to end the supposed affair—and even suggests welcoming Swan into their home for a polyandrous arrangement. Chantal calls her mother in a panic, and her parents come over to confront the fantasy man they’ve created. Gene’s suspicions grow stronger as they wonder if Robert Swan could be real.
After a careful dive into the matter, Chantal realizes that Swan is actually Gene’s father, Adam Wright, playing the role of her mother’s old lover. She and her mother decide to ride the prank to its conclusion, turning the tables on the men for a moment. Germaine discovers from John that he, Gene, and Adam had been in on the ruse from the start, and she concedes defeat while praising her husband for staying loyal to his sex. In the end, the family reconciles, and it’s revealed that Chantal is pregnant, just as Germaine suspected all along.
