Harriet is a British thriller author who recently relocated to New York City to live with her fiancé. Orphaned at age eleven, she struggles with feeling like an outsider to her fiancé's affluent world. She is highly observant and analytical, relying on her skills as a mystery writer to understand her new family. A dark secret from her childhood keeps her guarded and cautious.

Edward is the eldest living son of the wealthy Holbeck dynasty. He currently runs his own business independently of his family's massive corporate empire. He intentionally keeps his distance from his relatives, warning Harriet about their intense nature. He acts as a supportive partner as they prepare for the birth of their child.

Robert is the fiercely powerful patriarch of the Holbeck family and the head of their corporate empire. He lost his parents at a young age and was raised by his grandparents, adopting a ruthless approach to protecting his legacy. He tests outsiders rigorously before accepting them into his inner circle.

Matilda is the only daughter of the Holbeck family. She utilizes the family's immense influence casually, manipulating professional schedules just to secure a meeting. Despite her power, she presents a warm and welcoming demeanor to outsiders who pass the family's scrutiny.

Eleanor is the matriarch of the Holbeck family. She upholds classic, old-fashioned traditions and orchestrates the family's lavish gatherings at their estate, The Hydes. She acts as a buffer between her husband's intense nature and the rest of the family.

Oliver is Edward's younger brother who looks physically older due to the stress of his responsibilities. When Edward stepped away from the family business, Oliver took on significant roles within the company. He is highly competitive and deeply entrenched in the Holbeck corporate machinery.

Stuart is the youngest Holbeck brother. He is a recovering alcoholic who attends AA meetings. He was twelve years old when his oldest brother died, an event that deeply impacted his emotional development.

Fiona is Oliver's wife and a stay-at-home mother to their children. She is fiercely protective of her immediate family's inheritance and status within the larger dynasty. She completely commits to the bizarre Holbeck traditions to ensure her children secure their financial future.

Lila is Stuart's wife. She is a former model and actress originally from Sweden. She brings an outside perspective to the family, having been married previously to a Boston basketball player.

Bobby was the eldest Holbeck son who died at age twenty while attending Columbia University. He possessed progressive ideas that clashed with the traditional family business model. His death remains shrouded in silence and mystery within the family.

Billy is the young son of Oliver and Fiona. He is easily frightened by the family's intense traditions, particularly the Krampusnacht game and the history of Bobby's preserved childhood bedroom.

Samantha is a sixty-year-old woman who previously worked as a nanny for the Holbeck family. She signed a strict non-disclosure agreement regarding her time with the family and remains highly nervous when discussing them.

Deonte is a retired NYPD lieutenant. He consults with Harriet under the impression that she is researching scenarios for her upcoming thriller novel. He provides practical advice regarding blackmail and evidence.

Lucy was a young blonde college student at Columbia University. She went missing in 2002 around the same time as a major tragedy in the Holbeck family.

Ataahua is a Māori housekeeper employed by the Holbeck family. Eleanor sends her to Harriet's apartment to assist with daily chores so Harriet can focus on writing her novel.

Milo is Lila's son from her previous marriage to a Bostonian basketball player. He is brought into the intense Holbeck family traditions through his mother's marriage to Stuart.

Laurence is the man responsible for a devastating car crash that killed Harriet's parents when she was eleven years old. His actions permanently altered the course of Harriet's life.

Nunu is the current nanny for the younger generation of the Holbeck family. She handles childcare during the family's elaborate and stressful gatherings.

Louisa is Harriet's literary agent in London. She manages Harriet's career and requests writing extensions when Harriet struggles with her deadline.

Gianna was a college student at MIT who died under suspicious circumstances. Her death is investigated by Harriet as she attempts to unravel the Holbeck family mysteries.

Alison was a student at MIT whose death profoundly affected Gianna. She is another tragic figure connected to the family's past during the college years.

Aliza is a Lebanese artist who disappeared in 2020. Harriet finds an old photograph of her that links her to the Holbeck family's inner circle.

Melissa worked as a personal assistant to Stuart Holbeck. She operates remotely, making her physical disappearance easier to conceal from the outside world.