Stella is a 38-year-old best interest attorney specializing in representing children in complex custody cases. As a survivor of childhood trauma who experienced traumatic mutism, she brings a deep empathy and meticulous dedication to her work. She is currently undergoing an amicable divorce from her husband, Marco, and relies heavily on her lifelong mentor, Charles Huxley.

Rose is a nine-year-old girl at the center of an acrimonious custody battle. Following the traumatic death of her nanny, she suffers from traumatic mutism and refuses to speak. Despite her small stature, she is highly intelligent, a gifted piano prodigy, and exhibits deeply troubling behaviors that concern her family and legal advocates.

Beth is an affluent heiress and Rose's mother. She maintains a formal, highly controlled demeanor and insists on strict rules for her daughter's upbringing. Following the death of the family nanny, she claims to have developed a severe phobia of glass, prompting the removal of all glass from their sprawling Maryland estate.

Ian is Rose's father, a former landscaper who built his own landscaping company. He contrasts sharply with his wealthy wife, presenting a more casual and relaxed presence, though he harbors an undercurrent of anxiety. He seeks sole custody of his daughter and admits to having a brief physical affair with the deceased nanny.

Charles is a judge and former defense attorney who serves as Stella's primary father figure. He first met Stella when she was a teenager, offering her a job after she honestly returned a lost briefcase of money. He provides steady support and advice as Stella navigates the emotionally taxing Barclay case.

Harriet is Ian's mother and Rose's grandmother. She lives in her own dedicated wing of the sprawling Barclay estate, relying on a cane due to an old leg injury. While she attempts to present a calm and collected demeanor to outsiders, she openly expresses frustration with her son and asserts protective opinions regarding her granddaughter.

Tina is the former nanny for the Barclay family whose sudden, fatal fall from a third-story window initiates the events of the story. Prior to her death, she experienced strange occurrences in the house, received threatening notes, and engaged in a secret physical relationship with her employer.

Marco is an attorney who met Stella during their time at Georgetown law school. Married for ten years, the two are currently undergoing an amicable divorce. He remains a friendly presence in Stella's life, occasionally discussing legal cases with her over meals.

Pete is Tina's grieving boyfriend, a young man with dyed blonde hair and tattoos. He harbors deep resentment toward the Barclay family and the media for reducing Tina to simply "the nanny," and he tries to assist Stella's investigation by sharing videos and information about Tina's final days.

Detective Garcia is the lead police investigator assigned to Tina's cold case. She suspects the Barclay family is withholding information but lacks the evidence to press charges. She proves to be a valuable resource for Stella, eventually helping her access old police records concerning her own mother's death.

Dr. Markman is Rose's therapist. Initially guarded and cold, she softens upon realizing Stella is also a trauma survivor. She possesses a collection of Rose's disturbing drawings, which provide insight into the child's psychological distress.

Ashley is a friend of Tina's who works in the area. She holds crucial information about the final moments of Tina's life and uses her knowledge of the Barclay family's secrets to secure financial leverage for herself.

Lucille is Stella's caring neighbor. She fosters young animals and provides a safe, gentle environment that Stella briefly utilizes to help draw Rose out of her silent shell.

Stella's mother is a deceased figure whose memory heavily influences Stella's life. Following the tragic death of her husband, she succumbed to extreme grief, anxiety, and a fatal heroin addiction, leaving a young Stella to find her body.