Jackson is a middle-aged private investigator and former police officer. Having survived a childhood marked by profound tragedy, he uses his profession to find missing pieces and help people. He manages his investigative work in Cambridge while maintaining a devotion to his young daughter, Marlee, and trying to handle a messy divorce.

Sylvia is the eldest of the four Land sisters, originally a child who claimed to hear the voices of God and Joan of Arc. In the present day, she lives as a cloistered nun named Sister Mary Luke. She maintains a saintly composure but carries deep scars from a highly abusive, loveless childhood under her father's authority.

Amelia is the second-oldest Land sister, a reserved, bookish woman who teaches communication skills to trade school students. Affected deeply by her cold upbringing, she struggles to form connections and turns to gardening for comfort. The discovery of her missing sister's toy prompts her to seek professional answers.

Julia is the third Land sister, working as an occasionally employed actress and secret shopper. She possesses a highly mercurial and flirtatious personality that frequently clashes with Amelia's reserved nature. Despite their bickering, Julia feels protective toward her sister as they return to Cambridge to settle their father's estate.

Olivia is the youngest of the Land sisters, a sweet child fiercely loved and spoiled by her siblings. In 1970, she vanishes from her family's yard without a trace, leaving behind only questions. The sudden reappearance of her favorite toy decades later serves as the catalyst for Jackson's investigation.

Michelle is a young woman who reluctantly drops out of school to marry and have a child, finding motherhood bewildering and restrictive. Following a violent incident involving her husband Keith, she ends up serving time in prison. She later changes her name to Caroline, seeking a fresh start as a teacher in rural England while still carrying the weight of her past.

Theo is a widowed attorney who becomes consumed by grief after the tragic murder of his favorite daughter, Laura. Unable to move past the tragedy, he stops working, neglects his health, and turns his home into an incident room dedicated to her case. On the tenth anniversary of her death, he hires Jackson to find the killer.

Shirley is Michelle's sister, a woman with a thin dancer's build and a guarded demeanor. She approaches Jackson to track down her missing niece, Tanya, claiming she lost touch and wishes to reconnect. She presents herself as straightforward and professional, though she holds tightly to the details of her family's violent past.

Marlee is Jackson's eight-year-old daughter. She lives primarily with her mother and her mother's boyfriend, navigating a modern childhood full of pop culture references that constantly worry her protective father. She serves as Jackson's anchor and primary motivation to keep fighting for goodness in the world.

Josie is Jackson's ex-wife and Marlee's mother. She shares an acrimonious relationship with Jackson following their divorce, often clashing with him over his parenting choices and his tendency to bring his dangerous work into their daughter's orbit.

Victor is a retired Newnham College math professor and the patriarch of the Land family. He is a cold, authoritative figure who generates deep fear and resentment among his children. His recent death prompts his daughters to return home and clean out his estate, leading them to discover troubling items locked in his desk.

Rosemary is the mother of the Land sisters. Overwhelmed by her domestic responsibilities and trapped in an unhappy marriage to Victor, she finds her energetic older daughters exasperating and clearly favors her youngest child, Olivia.

Laura is Theo's beloved daughter, an energetic young woman taking a gap year before university. Her sudden and violent death in her father's office building leaves a lasting void in his life, serving as the central tragedy of the second case history.

Binky is an eccentric, crotchety elderly woman living in a crumbling estate next door to the Land family. Constantly misplacing her cats and contacting Jackson for help, she is viewed by him as a charity case, though she holds a sharp, dismissive view of her neighbors' past tragedies.

Quintus is Binky Rain's only living relative. He is a snobbish and rude man who frequently tries to assert dominance in social situations. He takes an immediate and intense disliking to Jackson during their brief encounters.

Lily-Rose is a young unhoused woman with brightly dyed hair who lives on the streets of Cambridge. She eventually forms an unexpected connection with Theo Wyre after intervening during a severe medical emergency, providing him with a new focus for his paternal instincts.

Tanya is the daughter of Michelle and Keith Fletcher. Following the violent dissolution of her parents' marriage, she was supposed to be cared for by her aunt Shirley, but contact was lost, prompting a search decades later.

Keith is Michelle's husband, living with her in a remote cottage. Their marriage is volatile and highly strained, culminating in a violent argument that alters the trajectory of his young family's lives forever.

Stan is Laura Wyre's former teacher. He harbors inappropriate fixations on his female students and exhibits a crass, unhappily married demeanor when Jackson questions him about the past.

Kim is Stan's ex-wife, a woman who befriended Laura Wyre when Laura babysat for her family. Having left the country before the murder, she provides Jackson with crucial memories of the neighborhood dynamics from that era.

Deborah is Jackson's diligent secretary. She manages his chaotic schedule, handles prospective clients, and keeps his private investigation business running smoothly while he operates in the field.

Jonathan is a wealthy local landowner who marries Caroline. He treats relationships as possessions rather than partnerships, bringing bratty stepchildren and a difficult mother into his new wife's life.

David is the new boyfriend of Jackson's ex-wife, Josie. He lives with her and Marlee, creating ongoing tension and jealousy with Jackson, who questions his influence over Marlee.

Niamh was Jackson's older sister who took on a maternal role after their mother's death. Her unsolved murder when Jackson was a child remains a defining wound in his life and fuels his protective instincts toward women and girls.

Francis was Jackson's eldest brother who failed to pick Niamh up from the bus stop on the day she was murdered. Consumed by misdirected guilt over her death, he died by suicide, leaving Jackson alone with their distant father.