Susan is a mother of four who willingly relinquished a well-paying job at an advertising firm to raise her children. She lives in a comfortable middle-class home with her husband, maintaining a dutiful and calm exterior. Despite her seemingly perfect domestic arrangement, she yearns for solitude and struggles with an indefinable restlessness that separates her from her prescribed roles. She attempts to establish a "Mother's Room" in her house before seeking absolute privacy elsewhere, treating her own need for independence as if it were a physical disability.

Matthew is a stable husband who provides a comfortable life for his family on a lucrative salary. He considers himself a fully engaged father and partner, routinely discussing the day's events with his wife rather than harboring unspoken resentments. He possesses a pragmatic, highly civilized view of fidelity, experiencing affairs but expecting the marriage to continue undisturbed. When Susan's behavior changes, he views her actions as unreasonable and attempts to fit them into conventional frameworks he can understand.

Sophie is a young German woman who joins the Rawlings household ostensibly to learn English, though she already speaks it well. She has a deep, fruity laugh and displays prominent dimples and white teeth. Cheerful and highly competent, she establishes a warm presence in the home immediately. Her natural aptitude for domestic duties makes her a seamless addition to the family's daily operations, and she effortlessly steps into the maternal void left by Susan's absences.

Michael Plant is a publisher whose name becomes a focal point in the Rawlings household. He represents the kind of conventional figure that the couple's social circle expects to find involved in a marital dispute. His presence in the narrative fits neatly into the civilized, predictable framework that Matthew understands, serving as a catalyst for discussions about the future of the marriage.

Harry is the eldest son of Susan and Matthew. He is raised in a comfortable middle-class environment and participates in the family's well-ordered daily routines. He occasionally mirrors his father's logical approach to household matters, such as helping to explain away his mother's unusual need for privacy to his younger siblings.

The twins are the youngest children in the Rawlings family. Their enrollment in school serves as a catalyst for a major shift in the household routine, leaving their mother to confront a quiet house for the first time in over a decade. They require constant, predictable affection that Susan occasionally struggles to provide.

Mrs. Parkes works for the Rawlings family, assisting with general household upkeep. She is a familiar presence who comfortably integrates with the other staff and family members. Her casual chatter occasionally irritates Susan, who seeks total quiet.