Esther Greenwood, a college student from Massachusetts, travels to New York to work on a magazine for a month as a guest editor. She works for Jay Cee, a sympathetic but demanding woman. Esther and eleven other college girls live in a women’s hotel. The sponsors of their trip wine and dine them and shower them with presents. Esther knows she should be having the time of her life, but she feels deadened. The execution of the Rosenbergs worries her, and she can embrace neither the rebellious attitude of her friend Doreen nor the perky conformism of her friend Betsy. Esther and the other girls suffer food poisoning after a fancy banquet. Esther attempts to lose her virginity with a UN interpreter, but he seems uninterested. She questions her abilities and worries about what she will do after college. On her last night in the city, she goes on a disastrous blind date with a man named Marco, who tries to rape her.

Esther wonders if she should marry and live a conventional domestic life, or attempt to satisfy her ambition. Buddy Willard, her college boyfriend, is recovering from tuberculosis in a sanitarium, and wants to marry Esther when he regains his health. To an outside observer, Buddy appears to be the ideal mate: he is handsome, gentle, intelligent, and ambitious. But he does not understand Esther’s desire to write poetry, and when he confesses that he slept with a waitress while dating Esther, Esther thinks him a hypocrite and decides she cannot marry him. She sets out to lose her virginity as though in pursuit of the answer to an important mystery.

Esther returns to the Boston suburbs and discovers that she has not been accepted to a writing class she had planned to take. She will spend the summer with her mother instead. She makes vague plans to write a novel, learn shorthand, and start her senior thesis. Soon she finds the feelings of unreality she experienced in New York taking over her life. She is unable to read, write, or sleep, and she stops bathing. Her mother takes her to Dr. Gordon, a psychiatrist who prescribes electric shock therapy for Esther. Esther becomes more unstable than ever after this terrifying treatment, and decides to kill herself. She tries to slit her wrists, but can only bring herself to slash her calf. She tries to hang herself, but cannot find a place to tie the rope in her low‑ceilinged house. At the beach with friends, she attempts to drown herself, but she keeps floating to the surface of the water. Finally, she hides in a basement crawl space and takes a large quantity of sleeping pills.

Esther awakens to find herself in the hospital. She has survived her suicide attempt with no permanent physical injuries. Once her body heals, she is sent to the psychological ward in the city hospital, where she is uncooperative, paranoid, and determined to end her life. Eventually, Philomena Guinea, a famous novelist who sponsors Esther’s college scholarship, pays to move her to a private hospital. In this more enlightened environment, Esther comes to trust her new psychiatrist, a woman named Dr. Nolan. She slowly begins to improve with a combination of talk therapy, insulin injections, and properly administered electric shock therapy. She becomes friends with Joan, a woman from her hometown and college who has had experiences similar to Esther’s. She is repulsed, however, when Joan makes a sexual advance toward her.

As Esther improves, the hospital officials grant her permission to leave the hospital from time to time. During one of these excursions, she finally loses her virginity with a math professor named Irwin. She begins bleeding profusely and has to go to the emergency room. One morning, Joan, who seemed to be improving, hangs herself. Buddy comes to visit Esther, and both understand that their relationship is over. Esther will leave the mental hospital in time to start winter semester at college. She believes that she has regained a tenuous grasp on sanity, but knows that the bell jar of her madness could descend again at any time.