Eileen, the narrator of the novel, is a 74-year-old woman looking back at the events she experienced 50 years ago as a 24-year-old. Eileen chooses to use pseudonyms when reflecting on her story. Young-Eileen lives in X-Ville with her alcoholic, abusive father and works at a male juvenile penitentiary named Moorehead. Her dream is to escape her repressive life and move to New York.
Eileen spends a lot of her time fantasizing about one of her male colleagues, Randy, who is silent and mysterious. One day, a new director of education named Rebecca Saint John is hired at Moorehead. Eileen quickly notices how smart and beautiful Rebecca is, and works to gain her friendship. When Eileen and Rebecca go out for a drink, Eileen ends up drunk and is abused by her father upon her return home.
A new inmate arrives at the faculty: Leonard Polk. Leonard killed his father in his sleep, and Rebecca is working with him, to let him meet his mother. Rebecca and Eileen plan to spend Christmas Eve together. When Eileen arrives at Rebecca's house, she is surprised to see the broken-down state it is in. She tries repeatedly to leave, but Rebecca stops her, finally admitting that the home belongs to Leonard Polk’s mother.
Rebecca tells Eileen that she has learned Leonard's motivation for killing his father: his father was raping him. Leonard’s mother was aware of the sexual abuse Leonard was enduring but decided not to report it, as she and her husband’s relationship was getting better. Eileen finds out that Rebecca showed up at Mrs. Polk's house in an attempt to secure a confession from her, but ended up attacking her and tying her up in the basement. Eileen agrees to help Rebecca coerce a confession from Mrs. Polk by using her father’s gun.
Mrs. Polk confesses, but Rebecca accidentally shoots Mrs. Polk in the arm. She and Rebecca agree on letting Eileen take control of the situation: she will kill Mrs. Polk and put the gun in her father’s hands. Rather than following through on this plan, Eileen leaves and drives Mrs. Polk out of the city, leaving her in the car by the side of the road. Eileen hitchhikes to New York and begins a new life under a new name.
Old Eileen is happy with the decision she made on the last day she spent in X-Ville.
