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You p-pathetic, self-important little man. Murder me? There's a m-mortal sin if ever there was. And then what? Suicide to escape the ignominy of hanging? Ah... your G-God will give you a hell of a time. All those years of piety, up in smoke because of me. Ah, ah, ah, monsieur, you c-can't go yet. You don't think I'd let you d-die on me, d-d-deprive me of my ultimate t-triumph? You see, if you d-don't succeed, I'm a free man. And even if you do, it will still be a v-victory of sorts, because in the eyes of the law, I would be innocent, whereas you and your reputation, your p-precious reputation... b-blown to bits.
~ Norton threatening Poirot.

Stephen Norton (also known as Mr. X) is the main antagonist of Agatha Christie's last Hercule Poirot novel, Curtain: Poirot's Last Case, and is one of the foremost antagonists of the whole novel series about Hercule Poirot. He disguised himself as an innocent man, but he is responsible for numerous murders Poirot investigates by manipulating innocent people to do dirty work for him while he himself escape justice.

Aidan McArdle portrays Norton in the TV episode adaption of Curtain, which is also the whole TV series' final episode. Therefore, Norton is the final villain of Poirot series, in both books and the TV series. 


Murder Case of X

Mr. X was a mysterious person who was unsuspected of involvement in five previous murders, in all of which there was a clear suspect. Four of these suspects have since died (one of them hanged); in the case of Freda Clay, who gave her aunt an overdose of morphine, there was too little evidence to prosecute. A heavily illed Poirot called the recently widowed Hastings to join him in solving this case, right inside a hotel which was once Styles Court, the place when Poirot and Hastings solved their very first teamwork case.

It was assumed that X is among the guests at Styles Court with them. Among them, there was Stephen Norton, a bird watcher. The old house was now under new owners, Colonel and Mrs. Luttrell. The guests know each other, with this gathering initiated when Sir William Boyd-Carrington invites the Franklins to join him for a summer holiday stay. The five prior murders took place in the area, among people known to this group.

While Hastings and Elizabeth are out with Norton, Norton claimed that he saw something that disturbed him through his binoculars, but he was always vague about whoever he saw. As Hastings drawing his conclusion, Norton was still concerned over what he saw days earlier when out with Hastings and Cole. As an advice, Hastings convinced Norton to confide in Poirot, to which Norton complied.

That night, Hastings is awakened by a noise and saw Norton entering his bedroom. The next morning, Norton was found dead in his locked room with a bullet-hole in the center of his forehead, the key in his dressing-gown pocket and a pistol nearby.

X VS. Poirot

- Poirot: Your proximity to these three murders was too much of a coincidence, and I smelt, as you say, the rat! That is why I came to Styles, to observe you function, and you have not disappointed, monsieur. No, you are a man who is very clever, but not clever enough for... [coughs] Hercule Poirot.
- Norton: So... what are you going to d-do about it?
- Poirot: [coldly] Execute you.
- Norton: [incredulous] Execute me?
- Poirot: Oui.
~ Poirot & X/Norton's final confrontation.

Unknown to Hastings, Norton was the real Mr. X, who confronted Poirot after revealing his true nature. As X, Norton demonstrated his abilities of psychological abuse upon people like Colonel Luttrell, Hastings and Mrs. Franklin, applying just such psychological pressure as was needed to provoke someone to commit murder. His victims were unwary what was happening when they were placed under Norton's control.

Fortunately, discovering Hasting was about to fall under Norton's control, Poirot intervened with sleeping pills in Hastings' hot chocolate that night, in order to avert a disastrous rash action. Ironically, Hastings had intervened in Mrs. Franklin's plan to poison her husband earlier, by turning a revolving bookcase table while seeking a book to solve a crossword clue (which was named Othello, one of the most famous tragedy by William Shakespere), thus swapping the cups of coffee, causing Mrs. Franklin to poison herself instead.

In the meantime, Poirot sensed that Norton had been deliberately vague about whom he had seen through the binoculars. He suspected that Norton would hint that he had seen Franklin and Judith, to implicate them in the murder of Mrs. Franklin, not inadvertent suicide as it was. This explained Poirot's testimony at her inquest, to ensure the police would stop their investigation.

Poirot's Victory

Would you mind awfully if I d-drank yours instead?
~ Norton's final words.

Given his very weak heart, Poirot realized that he must end the string of murders by killing Norton before his own time was up, since no evidence were applied to sue the killer. At their meeting, Poirot told Norton what he suspected. Norton confessed, and he challenged Poirot over blowing up the detective's reputation, since Poirot had no proof to prove Norton ever killed anyone.

However, Poirot revealed he would execute Norton. He gave Norton hot chocolate. Norton, arrogant and self-assured, insisted on swapping cups. Determined to stop Norton, Poirot had drugged both cups, knowing that himself had a higher tolerance for a dose that would put Norton to sleep.

After subduing Norton, Poirot carried the sleeping Norton back to his room using the wheelchair, dropping his feeble facade and could walk. Then, Poirot disguised himself as Norton by removing his wig and false mustache (something that was already demonstrated in The Big Four and foreshadowed in The ABC Murders), ruffling up his grey hair, then donning Norton's dressing-gown and walking with a limp.

Since Poirot was in the same height with Norton, he successfully convinced Hastings that Norton was alive after he left Poirot's room. Soon, Poirot shot Norton as Norton made one last smile, killing him, and locked the room with a duplicate key. Poirot passed away later on as his heart finally gave in.


Take my advice for the last time. Tell to Mademoiselle Cole all that I have said, that you also might have done what her sister did, had there been no watchful Poirot to stop you. Take the nightmare away, and show how Norton, not her sister, was responsible for the death of her father.

I have no more to say. Am I justified in what I have done? I do not know. I do not believe that a man should take the law into his own hands... but by taking the life of Norton, have I not saved others? I have always been so sure, but now... When the moment comes, I will not try to save myself, but humbly offer my soul to God and pray for His mercy. It is for Him to decide. Ah, Hastings, my dear friend. They were good days. Yes... they have been good days.

Hercule Poirot.
~ Poirot's final message to Hastings (TV Version).

Four months after Norton and Poirot's death, Hastings received a manuscript written by Poirot in his final moments. Poirot explains all about the murder case and its aforementioned solution, revealing the real X was none other than Stephen Norton, a man who had perfected the technique. In the letter, Poirot also compared Norton as Iago in Othello.

It was revealed that after killing Norton, Poirot then wrote his story on the letter and refused taking his amyl nitrite heart medicine. Believing he had to depend on God to judge his final act, Poirot felt complicated over his act to commit murder, but on balance he was convinced that he prevented Norton from harming more people. He believed it was the true way to enforce his justice.

By the end of the letter, Poirot suggested that Hastings should pursue Elizabeth Cole, a wish that was typical for a constant matchmaker like Poirot, before lamenting the lost days when everything between him and Hastings started in Styles Court and ended in the very same place, believing they were "good days".

After reading the letter, Hastings started to compare Norton's dying wound on his head as the Mark of Cain. The case of X was fully closed, as the legendary story of Hercule Poirot ends once and for all.



  • In the TV series, Norton was given a much more sympathetic backstory of being abandoned by his mother, which Poirot used to agitated him. However, in the original books, Norton was much less sympathetic and much more cruel, with no such backstory to begin with.
  • The Sleeping Murder, which is the last Marple novel, was released posthumously after Dame Christie's death, and long after Curtain was published. As a result, Norton is the last culprit that made appearance when Dame Christie was still alive, and the final antagonist of a Poirot novel, not the final antagonist of the entire shared novel universe created by Dame Christie.
    • However, the entire conception of Curtain was already conceived in 1940, 36 years before the novel final published in 1976 (not long before Dame Christie passed away in the same year).
  • Like Grace Springer, Mrs. Clapperton, Henry Reedburn, Harrington Pace, Sir Reuben Astwell, Paul Renauld, Simeon Lee, Lady Boynton, Leslie Ferrier, Cassetti, Lord Edgware, Madame Giselle and Paul Déroulard, Norton is presented as a murder victim, but their depraved nature and/or former crimes soon come to light in some parts of the stories.
    • Unlike the others above, Norton's twisted nature revealed before his death, not after. What is more, the man who killed Norton is none other than Poirot himself.


Agatha Christie's Poirot (title card).png Villains

Alfred Inglethorp | Alistair Ravenscroft | Ann Shapland | Anne Meredith | Bella Tanios | Claude Darrell | David Hunter | Dorothea Jarrow | Dr. Geoffrey Roberts | Dr. James Sheppard | Elsa Greer | Evelyn Howard | Franklin Clarke | Gerda Christow | Jacqueline de Bellefort | Jane Wilkinson | Jessie Hopkins | Josiah Bland | Katherine Martindale | Lady Westholme | Lanfranco Cassetti | Marthe Daubreuil | Martin Alistair Blunt | Michael Garfield | Miss Chadwick | Miss Gilchrist | Nick Buckley | Nigel Chapman | Norman Gale | Patrick Redfern | Rowena Drake | Simon Doyle | Sir Charles Cartwright | Stephen Norton | Superintendent Sugden
Short Stories
Marrascaud | Nurse Harris | Roger Havering | Zoe Havering

Villainous Victims
Abandoned Accomplices
Anne Morisot | Carlotta Adams | Eileen Corrigan | Leslie Ferrier
Lady Boynton | Lord Edgware | Simeon Lee
Angèle Blanche | Charles Trenton | Henry Reedburn | Leopold Reynolds | Louise Bourget | Madame Giselle
Lanfranco Cassetti | Mrs. Lorrimer | Paul Déroulard | Stephen Norton
John Christow | Linnet Doyle | Millicent Pebmarsh | Mrs. Clapperton | Paul Renauld | Sir Reuben Astwell

Accomplices & Others
Alice Cunningham | Anne Morisot | Big Four | Carlotta Adams | Christine Redfern | Countess Vera Rosakoff | The Crofts | Eileen Corrigan | Frances Cloade | Freddie Rice's husband | George Challenger | Henrietta Savernake | Hilde Martindale | Leslie Ferrier | Madame Daubreuil | Merlina Rival | Miss Van Schuyler | Rowley Cloade |

Sophie Hannah's Continuations
The Monogram Murders (2014): Jennie Hobbs | Nancy Ducane | Samuel Kidd

Adaptational, Homage & Non-Canonical
Agatha Christie's Poirot: Grace Springer | Harrington Pace | Marie McDermott | Sister Agnieszka |

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