Blythe is a writer living in an unnamed North American city who meets her husband in college. Haunted by her family's generational history of maternal neglect, she approaches motherhood with fierce determination but also deep-seated anxiety. When her daughter is born, she finds the physical and emotional reality of parenting intensely challenging and isolating, causing her to question her own instincts and sanity.

Fox is Blythe's husband, a highly successful architect who grew up in an idyllic, loving household. He holds traditional expectations of motherhood and desperately wants to recreate his own happy childhood for his growing family. His pragmatic, optimistic nature often prevents him from understanding or validating his wife's intense maternal anxieties.

Violet is Blythe and Fox's firstborn daughter. Intelligent and observant, she displays a marked preference for her father's company from an early age. Her precocious nature and sometimes unsettling behavior exacerbate her mother's insecurities about parenting.

Cecilia is Blythe's mother, a woman who never wanted to embrace the maternal role. After enduring a severely abusive childhood, she finds herself ill-equipped to raise a child and retreats into emotional detachment. She eventually abandons the family to reinvent her life in the city.

Etta is Cecilia's mother and Blythe's grandmother. Growing up in a rural setting in the mid-twentieth century, she suffers a severe tragedy early in her marriage. The subsequent grief and heavy reliance on sedatives destroy her capacity to care for her child, initiating a generational cycle of trauma.

Gemma is Fox's new partner and the mother of his youngest child. She exudes a natural, effortless maternal warmth that stands in sharp contrast to Blythe's struggles. She frequently attends a weekly mothers' group, completely unaware of the complex web of observation surrounding her.

Sam is Blythe and Fox's second child. He represents a fresh start for his mother, who instantly feels the miraculous, overwhelming rush of love she desperately desired but failed to experience with her firstborn.

Helen is Fox's mother. Warm, capable, and deeply involved in her family's life, she provides the template for the perfect mother that Fox expects. She attempts to help Blythe survive the grueling early weeks of parenting but ultimately believes mothers must carry the burden themselves.

Seb is Blythe's father. A former hotel doorman who falls in love with Cecilia in New York City. He insists on keeping their child despite Cecilia's objections, ultimately raising Blythe as a single father after his wife's departure.

Louis is Etta's first husband and Cecilia's biological father. He abandons his medical studies to work on a family farm at the insistence of his father-in-law, a decision that leads to a catastrophic farm accident.

Henry is Etta's second husband. He steps in to provide for the family financially but remains largely passive in the face of his wife's deteriorating mental state and abusive behavior toward her child.

Mrs. Ellington is a kind neighbor from Blythe's childhood who lives three doors down. She provides small glimpses of domestic normalcy and maternal kindness during periods when Blythe's own mother is absent.

Jet is Gemma and Fox's infant son. A cheerful toddler who lives with his parents and shares a striking physical resemblance to other members of the family.