Tully is the eldest daughter of Stephen and Pamela Aston. She lives a seemingly perfect, affluent life as a wife and mother in a pristine mansion, but beneath her composed exterior, she battles severe anxiety. She hides a lifelong compulsion for shoplifting, which she uses as a physical release for her stress and feelings of powerlessness. Her carefully structured world faces imminent collapse when she discovers her husband has lost their savings in a bad investment.

Rachel is Stephen and Pamela's younger daughter, working as a successful professional baker who specializes in elaborate cakes. She presents a calm, capable demeanor that contrasts heavily with her sister's overt anxiety, but she privately carries the weight of a severe trauma from her teenage years. She relies on the methodical nature of baking and compulsive eating as ways to exert control and suppress painful memories, avoiding romantic intimacy entirely.

Heather is an interior designer who is significantly younger than her fiancé, Stephen, and even younger than his adult daughters. Having survived a deeply violent childhood, she seeks safety, stability, and a sense of family in her relationship with the older, established doctor. She struggles with insecurity about her working-class background and sometimes uses alcohol to cope with painful memories and her growing doubts about Stephen.

Stephen is a wealthy, highly respected heart surgeon and the patriarch of the Aston family. He recently moved his wife, Pamela, into an assisted living facility due to her Alzheimer's disease and quickly initiated a romance with Heather. He presents a charming, affable public persona that commands respect in his affluent community, though he maintains a tight, quiet grip on his family's dynamics and decisions.

Pamela is Stephen's wife and the mother of Tully and Rachel. She lives in a secure assisted living facility due to early-onset Alzheimer's disease, which causes severe memory loss, confusion, and disorientation. Her cognitive decline leaves her highly vulnerable, though she occasionally experiences moments of striking lucidity that hint at unacknowledged family history and hidden fears.

Sonny is a barrister and Tully's husband. He initially appears stable and dependable, though his recent poor financial investments have secretly cost the family their fortune, placing immense strain on their marriage and lifestyle. He loves his family but struggles to understand the true depth of his wife's underlying anxiety and secretive behaviors.

Darcy is a charming, witty delivery driver who works with Rachel. Having experienced his own significant setbacks, including the failure of his cafes during the pandemic, he maintains a kind and highly nonjudgmental attitude. His gentle flirtation offers Rachel a safe environment to consider opening up about her past.

Fiona Arthur is an enigmatic woman whose name is discovered on a hidden note alongside a large sum of cash in one of Pamela's old hot-water bottles. Her connection to the Aston family remains a total mystery to Stephen's daughters, sparking Rachel's investigation into their father's past.

Miles is the three-year-old son of Tully and Sonny. He is sensitive to the unspoken tension in his household and begins exhibiting anxious behaviors, screaming tantrums, and an eventual refusal to speak as his parents' stress levels rise.

Locky is the younger son of Tully and Sonny. He is a typical young child who inadvertently blurts out family secrets to relatives, adding to his mother's ongoing anxiety about maintaining their perfect public image.