Sophia is a 15-year-old girl living on a dilapidated farm in Prince Frederick, Maryland, in 1965. She endures grueling physical labor and harsh treatment from her guardian, finding her only solace in academics. When she secures a full scholarship to the elite, predominantly white West Oak Forest Academy, she dyes her red hair black and escapes the farm to start a new life. At school, she faces intense racial hostility but discovers a talent for basketball and begins investigating fragmented memories of her early childhood.

Ozzie is a 19-year-old Black man from South Philadelphia who enlists in the US Army in 1948. He hopes to capitalize on the recent military desegregation orders to build a respectable career in intelligence. Despite scoring perfectly on his aptitude tests, he is assigned to menial maintenance work in postwar Germany. He struggles to manage his frustration with systemic racism, his promises to his mother regarding alcohol, and the heavy responsibilities that come with an overseas romance.

Ethel is a Black journalist and army officer's wife stationed in Mannheim, Germany, in 1950. After receiving a medical diagnosis confirming she cannot bear children, she experiences a spiritual awakening that redirects her maternal desires. She discovers an orphanage filled with abandoned biracial children and channels her journalistic skills and fierce compassion into creating a one-woman adoption agency to find them homes in America.

Ma Deary is the harsh matriarch of the Maryland farm where Sophia lives. She views Sophia primarily as unpaid labor, restricting her food, policing her behavior, and intentionally hiding her acceptance letter to boarding school. She maintains strict secrecy regarding her family's past and responds to questions with anger and physical discipline.

Jelka is a young German woman carrying significant trauma from World War II. She enters a relationship with Ozzie while her violent husband, Gottfried, is imprisoned in a Soviet camp. When she becomes pregnant with Ozzie's child, she faces severe social ostracism, loss of employment, and police harassment, forcing her to make agonizing decisions to protect her infant daughter.

Willa is one of the few Black students at West Oak Forest Academy. Coming from an affluent and highly supportive family in Washington, DC, she possesses an extensive wardrobe and natural confidence. She serves as Sophia's introduction to boarding school life, though their friendship experiences friction as they navigate the school's social landscape.

Max is a handsome, confident Black student at West Oak Forest Academy. Adopted from a German orphanage by a school teacher, he carries physical scars from a childhood fire. He forms a quick connection with Sophia over their shared status as minority students and becomes a crucial ally in her search for answers about her past.

Rita is Ozzie's ambitious and intelligent girlfriend. Motivated by a tragic incident of racial violence in her family, she is determined to become a lawyer and actively pursues higher education. She expects excellence from the people around her and refuses to let Ozzie's personal struggles derail her professional and social ascent.

Katja is the biracial infant daughter of Ozzie and Jelka. Her existence in postwar Germany places her in immediate danger due to widespread racism and the hostility of Jelka's family. She becomes the central focus of Ozzie's life, as he photographs her weekly and spends his weekends sleeping on the floor beside her.

Walter is Sophia's older brother, who works alongside her on the Maryland farm. Recognizing that Sophia's scholarship offers a rare opportunity for escape, he risks Ma Deary's wrath by stealing the family car to drive Sophia to the academy campus.

Bert is Ethel's husband, serving as a Black officer in the US Army stationed in Germany. He provides steady, practical support for Ethel's sudden mission to adopt multiple children from the orphanage, taking the massive expansion of their family in stride.

Tom Petty is a white, Southern first sergeant at Sullivan Barracks in Germany. He embodies the systemic racism within the military structure, consistently finding reasons to humiliate Ozzie and restrict his movements, demonstrating that federal desegregation orders do not change local leadership behavior.

Sister Ursula is an English-speaking Catholic nun running St. Hildegard's orphanage in Germany. She cares for the abandoned biracial children and eagerly accepts Ethel's offers of assistance, working alongside her to arrange adoptions.

Morgan is a fellow Black soldier who goes through basic training and deployment with Ozzie. He also scores highly on aptitude tests but is similarly denied advancement. He serves as Ozzie's primary friend and confidant during their time in Germany.

Nettie is Ozzie's mother, living in Philadelphia. Haunted by the damage her husband's addiction caused their family, she is fiercely protective of her children and demands that Ozzie swear off alcohol entirely while serving in the army.

Patty is a white student at West Oak Forest Academy who deeply resents the school's integration. She leads a clique of girls who relentlessly mock Sophia's clothing, background, and race, culminating in physical harassment in the locker room.

Jutta is Jelka's younger sister in Germany. She acts as a messenger between Jelka and Ozzie, helps take family photographs, and assists in caring for the baby when societal pressures overwhelm Jelka.

Julia is a fellow African American army wife stationed in Mannheim. She becomes Ethel's close friend and sounding board, encouraging her to use her journalism background to write the adoption guides that launch the "Brown Baby Plan."