Mamah is a highly educated translator and mother living in Oak Park, Illinois. Though initially content in her marriage, she feels unchallenged intellectually until she meets Frank. Her desire for self-actualization and personal freedom conflicts with the societal expectations placed on women in the early 20th century.

Frank is a controversial but brilliant American architect known for his "Prairie style," which emphasizes harmony with nature. He is charismatic, driven by his artistic vision, and deeply committed to living his truth. He readily ignores societal conventions to pursue his architectural and personal passions.

Edwin is Mamah's kind, reliable husband who draws contentment from simple routines, such as smoking Cuban cigars and tinkering with his automobile. He values order in his life and household. When his marriage faces serious challenges, he attempts to keep his family intact, revealing his deep devotion to his children.

Lizzie is Mamah's pragmatic sister who works as a teacher and helped fund Mamah's graduate education. She prefers a quiet, respectable life and often steps in to manage family responsibilities. She serves as a grounding force in the family but struggles with the public scrutiny brought on by Mamah's unconventional choices.

Catherine is Frank's wife and the mother of his six children. She represents the traditional domestic sphere that Frank rebels against. Her steadfast refusal to grant Frank a divorce deeply impacts the trajectory of Frank and Mamah's relationship, as she paints herself as a loyal wife in the face of public scandal.

Ellen is a prominent Swedish philosopher and a leading figure in the Woman Movement. Her writings on love, marriage, and female independence deeply resonate with Mamah. She becomes a powerful intellectual influence in Mamah's life, though her views prioritizing motherhood sometimes create ideological friction.

Mattie is Mamah's college roommate and close confidant. Living in Boulder, Colorado, she provides a temporary refuge for Mamah. While she is a loyal friend, Mattie also serves as a voice of caution, warning Mamah about the potential consequences of leaving her family and the harm it could cause.

John is Mamah and Edwin's young son. He is deeply affected by the shifts in his family dynamic and his mother's absences. He finds comfort in animals, particularly a stray dog he adopts, and relies on his sister for companionship.

Martha is Mamah and Edwin's daughter. Like her brother, she attempts to understand the complexities of her parents' changing relationship. She is often shy but remains hopeful about her family's future.

Anna is Frank Lloyd Wright's mother and a cofounder of the Nineteenth Century Woman's Club. Having endured her own difficult marriage to an unreliable man, she is deeply protective of her son but initially cold toward Mamah, fearing the scandal will bring further humiliation.

Taylor is one of Frank's architectural assistants. He travels with Frank and Mamah during their time in Europe, offering a friendly presence. He shares Frank's appreciation for art and helps Mamah learn to use a camera during their hikes.

Alden is Mattie's husband, living in Colorado. He is welcoming to Mamah during her stay and engages her in thoughtful conversations about women's roles and societal expectations.

Ernst is a German publisher working with Frank to produce a monograph of his architectural drawings. He is professional but uncomfortable with the unconventional nature of Frank and Mamah's relationship.

Else is a waitress in Berlin who offers Mamah comfort and introduces her to a circle of artists and poets. She represents the bohemian, non-judgmental European lifestyle that appeals to Mamah.

Billy is the foreman overseeing the construction of Frank's new Wisconsin home, Taliesin. He manages the crew and frequently interacts with Mamah as she takes on responsibilities around the site.

Lucky is a stray dog that young John Cheney adopts. He provides comfort and companionship to the children during a period of family upheaval, becoming a cherished pet.