The wealthy, elderly patriarch of the Lee family. Though confined to his room by age and physical frailty, Simeon possesses a domineering personality and derives amusement from manipulating his financial control over his dependent relatives. He values power over affection, treating his fortune—symbolized by a collection of uncut diamonds from his days in South Africa—as a tool for psychological cruelty.

A stolid, methodical local police officer. Superintendent Sugden embodies the traditional, procedural approach to law enforcement, building his case through careful collection of alibis, timelines, and physical evidence. He commands authority and approaches the chaotic Lee family with calm professionalism when called to investigate events at Gorston Hall.

A world-famous Belgian detective visiting the English Midlands for the holidays. Poirot relies on order, method, and an understanding of human psychology rather than mere physical clues. He approaches crime as a human drama, focusing heavily on the victim's character and the intense passions of those connected to him.

The dutiful eldest son of Simeon Lee. Alfred sacrificed his military ambitions to remain at home and manage the family business, enduring his father's constant bullying with a quiet, pained devotion. He serves as the primary caretaker of the estate but feels overshadowed by his estranged brother's sudden return.

A sensitive artist who has been estranged from his family for twenty years. David harbors a deep hatred for his father, holding Simeon responsible for his late mother's unhappiness. He only returns to Gorston Hall at his wife's urging, though the house immediately awakens his past traumas, particularly when he visits his mother's old sitting room.

The charming, roguish prodigal son of the Lee family. Harry shares his father's boisterous energy and rebellious streak, having lived a life of adventure and minor scandals abroad. His sudden return disrupts the household, especially frustrating his dutiful brother Alfred.

A striking young woman traveling from Spain to England to meet her grandfather for the first time. Proud and pragmatic, she carries a casual acceptance of violence from her time in civil war-torn Spain. She quickly captures her grandfather's favor with her blunt honesty and beauty.

A confident forty-year-old traveler arriving from South Africa. He introduces himself to the Lee family as the son of Simeon's old business partner, Ebenezer Farr. Though he claims to be visiting out of respect, his arrival at Gorston Hall creates immediate tension and confusion among the household staff.

The intelligent, graceful wife of Alfred Lee. Lydia recognizes Simeon's malice and maintains a polite but cool detachment to protect herself and her husband. She finds solace in creating meticulous miniature rock gardens on the estate's terrace, asserting order in a chaotic household.

A sensible, maternal woman who acts as an emotional anchor for her traumatized husband. Hilda sees through the dysfunctional dynamics of the Lee family and serves as a quiet voice of reason, though she quickly realizes the danger of returning to the oppressive estate.

A pompous and avaricious Member of Parliament. George is highly concerned with public appearance and respectability, though his primary motivation is securing his inheritance. He heavily relies on an allowance from his father, making him highly susceptible to Simeon's threats.

George's beautiful, much younger wife. Magdalene presents a facade of childlike innocence and sensitivity, but she is secretly burdened by debt and a hidden past. She views the family gathering entirely as a financial necessity and dreads Simeon's abrasive presence.

The elderly, devoted butler of Gorston Hall who has served the Lee family for nearly forty years. Tressilian represents tradition and order in the household, though his failing eyesight and sense of déjà vu make the sudden influx of guests deeply disorienting for him.

Simeon Lee's personal valet and attendant. Horbury possesses a furtive, cat-like demeanor that makes many in the household distrust him. He attends to Simeon's daily physical needs while nursing a deep fear of the police due to secrets from his past.

The chief constable of Middleshire. Colonel Johnson is a traditional, honorable law enforcement official who recognizes his friend Poirot's unique talents and quickly invites the detective to assist with the investigation at Gorston Hall.

Sydney Horbury's girlfriend in the local town. She provides Horbury with an alibi for the evening of the murder by attending the cinema with him.

The Lee family's solicitor. He handles Simeon's affairs, including drafting the new will that Simeon loudly requests on Christmas Eve to provoke his children, and later reading the final documents to the surviving family.

A footman working at Gorston Hall under Tressilian's supervision. He assists with the household duties during the busy holiday gathering.