After discovering that she is losing hair at an alarming rate, Marge visits Dr. Hibbert, who informs her that stress is the cause. The Simpson family decides to hire a nanny who can help clean the house and take care of the children. They start interviewing candidates, but none of them are right for the job (as Homer believes every candidate is a man in drag, à la Mrs. Doubtfire). Bart and Lisa sing a song about what they would consider to be the perfect nanny, and their wishes are answered when a woman with an umbrella glides down from the sky and introduces herself as Shary Bobbins, an obvious parody of Mary Poppins, which she vehemently denies. She seems perfect and is immediately hired.
Shary Bobbins proves to be very helpful for the Simpson family, helping the kids clean their rooms, singing them to sleep, and even making Mr. Burns happy. Marge recovers from her stress, and her hair returns to normal. The next day, as the reformed Simpsons sit down to a perfect dinner, Shary Bobbins declares that her work is finished and leaves the house. Just as she is starting to miss the Simpson family, she sees Homer strangling Bart as they are smashed through the living room window, Maggie attempting to put out a fire, and Marge losing her hair again; the family has instantly reverted to its previous state of dysfunction. Shary realizes that she must stay.
The family now starts to treat her rudely and lose interest in her songs and zest for life. Declaring that the Simpsons would be the death of her, she becomes depressed and starts drinking (while singing "Margaritaville") with Barney. The family realizes that they have "crushed her gentle spirit", and Marge admits to Shary that nothing can be done to change the Simpsons; through song, the family state that they are happy just the way they are. Shary accepts this, and leaves using her magical umbrella. As Shary glides away, Lisa asks whether they will see her again, and Homer is positive that they will; both unaware that behind them, Shary is sucked into a jet engine.