Catherine is the eldest Merton sibling and a successful dermatologist. Raised as her parents' favorite child, she grew accustomed to an entitled lifestyle and places a high value on maintaining the appearance of a perfect upper-class family. She struggles with infertility and expects to inherit the luxurious family estate, a dream threatened by her father's sudden decision to sell the house.

Dan is the middle Merton sibling who previously worked at his father's robotics company with the expectation of eventually taking over. After Fred spitefully sells the business, Dan is left unemployed and secretly drowning in debt from a high-risk private mortgage deal. He frequently drives around late at night to cope with his depression and the smoldering anger he harbors toward his emotionally abusive father.

Jenna is the youngest Merton sibling and an aspiring sculptor who relies entirely on her parents' generous monthly allowance to live in the city. Rebellious and volatile, she deliberately antagonizes her upper-class family by bringing home inappropriate boyfriends and creating avant-garde art. Her financial security is jeopardized when her father criticizes her lack of dedication and threatens to cut off her funding.

Fred is the wealthy, retired founder of a massive robotics company and the patriarch of the Merton family. He is a domineering, cruel man who treats his children with cold detachment, frequently using his $30 million fortune to control and humiliate them. His sudden announcement that he intends to sell the family estate and heavily alter his will sends his family into a panic.

Sheila is Fred's wife and the mother of Catherine, Dan, and Jenna. She presents the outward appearance of a composed society matron, but she privately relies on prescription anti-anxiety medication to handle her stressful household. She generally acts as a passive enabler to her husband's verbal abuse, maintaining the status quo of their toxic family dynamic.

Audrey is Fred's sister and the aunt of the Merton siblings. She misses the family's Easter dinner while recovering from a severe flu. She harbors long-standing bitterness toward her brother and believes she is owed a substantial portion of his fortune for keeping a dark family secret from their childhood on a Vermont farm. She quickly appoints herself as an amateur investigator following the murders.

Rose is an ambitious, high-profile attorney and Catherine's close friend since high school. Despite her professional success, she secretly harbors intense jealousy regarding the Mertons' generational wealth and societal advantages. She is currently entangled in a fraudulent real estate investment scheme that threatens her career, desperate for a quick financial windfall to cover her tracks.

Ellen is Rose's mother, a friend of Audrey Stancik, and a former secretary at Fred Merton's robotics firm. She is generally grounded and practical, though she worries extensively about her daughter's well-being and high-stress career. She observes the toxic Merton family from the periphery, acutely aware of how their vast wealth corrupts those around them.

Ted is a dentist married to Catherine. Having grown up with an abusive father, he despises the tense, hostile environment of the Merton family holidays and dreads their gatherings. He acts as a grounding presence for his wife but increasingly questions her cold, pragmatic reactions to family tragedies.

Lisa is Dan's supportive wife. She is aware that her husband is struggling with depression after losing his job, but she does not know the full, catastrophic extent of their financial ruin. As the police investigation intensifies, she grows increasingly stressed by Dan's erratic behavior and his inability to account for his whereabouts on the night of the murders.

Jake is Jenna's current boyfriend. He plays the role of a heavily-tattooed, starving artist, deliberately brought to the Easter dinner to infuriate Jenna's conservative parents. He is opportunistic and quickly recognizes the potential financial benefits of being romantically linked to a soon-to-be wealthy heiress.

Irena is the Mertons' longtime part-time housekeeper who previously served as the children's nanny. She feels a deep, maternal affection for Catherine, Dan, and Jenna, having practically raised them in place of their emotionally distant parents. She is fiercely protective of the siblings, willing to risk her own freedom to shield them from police scrutiny.

Detective Reyes is a methodical police investigator assigned to the Merton homicide case. Upon viewing the brutal crime scene, he immediately deduces that the violence was personal rather than a random robbery. He works diligently to untangle the shifting alibis and blatant falsehoods presented by the wealthy suspects.

Detective Barr is Detective Reyes' partner on the Aylesford police force. He is highly skeptical of the Merton family's supposed grief, taking note of the severe lack of sentimentality in the victims' home. He pushes the siblings hard during interrogations, refusing to be intimidated by their wealth or social status.

Walter is the Merton family attorney tasked with managing Fred's $26 million estate. He handles the legal fallout of the murders and is forced to deliver unexpected, highly contentious news to the surviving family members regarding the specifics of Fred's will.

Caroline is Walter's wife and an acquaintance of Sheila. She provides the detectives with an outsider's perspective on the toxic dynamics inside the Merton household, noting Fred's inherent cruelty and Sheila's reliance on hidden medications.

Janet is a junior associate at Walter Temple's law firm who attended law school with Rose Cutter. She inadvertently leaks confidential information regarding the Merton estate over drinks, setting off a dangerous chain of events driven by financial greed.

Carl is a small-time drug dealer who lives with his mother. He drives a distinctive pickup truck with flame decals, placing him in the wealthy Brecken Hill neighborhood on the night of the murders and making him a crucial eyewitness for the police.