Agatha Christie



"Donna: Agatha, people love your books, they really do, they’re gonna be reading them for years to come. Agatha: If only! Try as I might it’s hardly great literature, now that’s beyond me. I’m afraid my books will be forgotten, like ephemera."

- Doctor Who, "The Unicorn and the Wasp"

The Queen of the classic mystery, ranked with Arthur Conan Doyle as the greatest mystery writer of all time. Her stories are elaborately plotted puzzle pieces, full of false identities and faked deaths. She enjoyed a very long career; her first novel, The Mysterious Affair at Styles, was published in 1920, while her final novel, Sleeping Murder, was published posthumously in 1976. Among the best-selling authors of all time.

Her principal detectives were:


 * Hercule Poirot, a retired Belgian police detective turned P.I. Fastidiously neat, he pretended to be a Funny Foreigner in order to put his clients and suspects off their guard. Agatha Christie herself eventually tired of the character, but since fans enjoyed him, she continued to write Poirot stories. He appeared in 33 novels and 51 short stories.
 * Miss Jane Marple. Seemingly a fluffy old spinster, her mind was as sharp as her knitting needles; having lived in small towns her whole life, nothing about human nature ever surprised her. She appeared in 12 novels and 20 short stories.
 * Tommy and Tuppence Beresford, a husband and wife team. Their adventures were more like spy novels than straight mysteries, though they did contain elements of classic detective novels. They appeared in five books: four novels and a short story collection, Partners in Crime.

Christie also wrote 16 novels which did not feature any of her series detectives. These ranged from traditional mysteries with one-shot detectives to Thrillers which placed more emphasis on action than detection. The latter were almost universally the most poorly received of Christie's works.

While most of the stories are nominally set in the year of publication, in practice they all take place in the time of the Genteel Interbellum Setting. Of Christie's series detectives, only the Beresfords age in real time. Poirot and Marple both begin as elderly characters and over the course of Christie's 56-year career, age roughly 20 years at most. (This matches a line from the final Poirot novel Curtain, in which it is stated that it has been "over twenty years" since the first adventure, The Mysterious Affair at Styles, which came out in 1920 and presumably was set in the present day.)

Christie possessed an uncanny ability to subvert the reader's expectations. Being well aware of the mystery conventions of the time, she was frequently able to subvert them for a Twist Ending. For example, Christie knew that there were certain characters, who by virtue of their role in the story, the reader would not suspect. To drive home the point that the reader should suspect everybody, she would frequently make one of these characters the murderer, writing books where (all examples might not be listed):


 * The way too obvious suspect (who therefore of course won't turn out to be the real killer, now will they?) really was the killer after all, ( ), ('), ('), (arguably '), ('), ()
 * everyone was guilty, ()
 * the narrator was guilty, ('), ('), (),
 * one of the sleuths investigating the mystery was guilty, ('), ('), ( ), ()
 * one of the murder victims was guilty, ('), (')
 * the supposed intended target was guilty, ('), ('), ('), (')
 * a child was guilty, ()
 * the murders looked like the work of an Ax Crazy killer, but the murderer was neurotypical,()

She invented most of the above twist endings. For a list of her works see: Agatha Christie Bibliography

Most of the books in the main series have been televised, and many filmed, some repeatedly. There's even an Anime Crossover of Poirot and Miss Marple.

Christie works which have their own pages

 * The ABC Murders
 * And Then There Were None
 * Death on the Nile
 * Five Little Pigs
 * The Mousetrap
 * Murder at the Vicarage
 * A Murder Is Announced
 * The Murder of Roger Ackroyd
 * Murder on the Orient Express
 * The Mysterious Affair at Styles
 * Sad Cypress

This author's works include examples of
""She cares too much, that little one.""
 * Adaptation Decay: She parodied this in her novel Mrs McGinty's Dead, where her Author Avatar, Adriane Olivier works on a theatre adaptation of her book, and she complains that the characters are completely changed.
 * Ironically in real life, Agatha Christie's main complaint about early stage adaptations of her plays was that they stuck too closely to the books, as she felt that a murder mystery should surprise people.
 * Adjective Animal Alehouse: The titular Pale Horse in The Pale Horse.
 * Amateur Sleuth: Miss Marple; Emily Trefusis in The Sittaford Mystery.
 * Ambition Is Evil: Turns up in several Christie works.
 * Anyone Can Die: And in some cases, everyone
 * Asshole Victim: Two prominent examples are Murder on the Orient Express and Appointment with Death.
 * Interestingly subverted in Evil Under the Sun: while the victim is disruptive in the community and has personality issues, to put it mildly,
 * A good subversion in Towards Zero too - the victim is a good, caring and hospitable (if a tad old-fashioned) person, and her death serves as Moral Event Horizon in-universe, which is
 * Author Appeal: Christie's second husband was an archaeologist, and Christie eventually developed a strong interest in the subject herself. Not surprisingly, several of her mid-period novels reflect this interest either by taking place at an archaeological dig (Murder in Mesopotamia) or by simply having such a setting as the background (Appointment with Death). This interest eventually led Christie to actually set one novel in ancient Egypt itself (Death Comes as the End).
 * Author Avatar: Ariadne Oliver
 * Author Filibuster: Christie novels tended to have long Start to Corpse times, something which she was occasionally criticized for. She used the first chapter of Towards Zero to respond to these criticisms by having a character deliver a lengthy speech on how a murder is the culmination of a murderer's plot rather than the instigating point, and thus should come as late in the book as possible.
 * Beam Me Up, Scotty: Christie was reputed to have said "The great thing about being married to an archaeologist is that the older you get, the more interested he becomes in you." However, there is no real evidence that she actually uttered the quote.
 * The lady herself explicitly denied saying it, adding that she thought it "a very silly thing to say."
 * Because I'm Jonesy: The denouement of "The Oracle at Delphi".
 * Better Manhandle the Murder Weapon: How the Obvious Suspect becomes the Obvious Suspect in "The Shadow on the Glass".
 * Beware the Nice Ones: Where to begin?
 * Big Screwed-Up Family: Death Comes as the End
 * Christie used this trope quite a bit. Other examples would be Appointment with Death, Crooked House, and A Pocket Full of Rye.
 * Bitter Almonds
 * Blackmail The quickest way to become the next corpse.
 * Black Sheep: sometimes appears in Big Screwed-Up Family situations.
 * Death Comes as the End: Sobek, the second son, is a hard-drinking womanizer who wastes money on expensive dancing girls.
 * A Pocket Full of Rye: Lancelot Fortescue, who was turned out of the family business and moved to Kenya.
 * Bowdlerise: And Then There Were None was originally titled Ten Little Niggers, then retitled Ten Little Indians, then retitled yet again when that title was recognised as offensive.
 * Brother-Sister Incest:
 * Bunny Ears Lawyer: Poirot's many eccentricities are compensated by his exceptional skills as a detective.
 * Busman's Holiday: Poirot, all the time, and even Marple occasionally. The lesser-known Parker Pyne suffered from it even more than Poirot did.
 * The Butler Did It: Several times, in different variations, both straight and skewed (for instance: the butler did it, but he wasn't really a butler).
 * Canon Welding: Christie's main detectives never crossed over, but several minor characters did, effectively tying the majority of her detective fiction into the same universe. See the article on this trope for more information.
 * Celibate Hero: Although Poirot never has a romantic/sexual relationship of any kind, he is more a Celibate Hero of the "Love is a Distraction" variety than a true asexual. He typically acts gallant towards the women he meets -- much more so than, say, Sherlock Holmes in similar situations -- and he often makes polite comments about their looks and/or fashion choices; Hastings even jokingly remarks in Curtain: Poirot's last case that the detective prefers showy, voluptuous redheads. It never goes beyond that, though.
 * Note also that Poirot is portrayed as a devout Catholic, so it makes sense that he would avoid sex without marriage.
 * Poirot does seem to be attracted to Countess Vera Rossakoff. However, their relationship never develops beyond a mild flirtation.
 * There's also Miss Marple, who has never been married, and whose love life, past or present, is rarely ever discussed. In A Caribbean Mystery, in discussing a girl who was encouraged to date a young man her parents approved of (after she broke up with an objectionable boyfriend), Miss Marple reflects on a young man she once dated who seemed very exciting, until he was warmly welcomed by her father. (She found him very boring after that.)
 * It might be interesting to bear in mind that "dating" didn't always carry the same connotations in the Victorian England Marple grew up in, and that the full and literal meaning of "old maid" (a term repeatedly used to describe Marple) is "old (female) virgin".
 * Cerebus Rollercoaster: Christie wrote her most serious and psychological works (like Five Little Pigs) in the middle of her career, in the 1940s. Her earlier and later stories, are, in general, more lighthearted.
 * Closed Circle: In Murder on the Orient Express.
 * Clueless Mystery: How the clues go together is usually made impossible for the reader to divine until the detective states it.
 * Although the clues themselves will pretty much always point to the right person. The thing left out is usually details in their motivation.
 * Connect the Deaths: Frequently used as a Red Herring; at least three novels feature murderers setting up a false pattern to conceal the true motive behind the crime.
 * Covers Always Lie: Subverted. Christie was greatly displeased with the original artwork for the cover of The Man in the Brown Suit; she felt it was both horribly done and intentionally misleading. From then on, all covers of the original editions required her final approval.
 * Creator Backlash: Christie repeatedly said that The Mystery of the Blue Train was the worst book she ever wrote. However, the book was popular with fans and received positive reviews from critics.
 * Too bad she never wrote about trains again...right?
 * Creator Breakdown: Christie disappeared for ten days in late 1926 due to emotional issues resulting from the breakdown of her first marriage. Her creative focus momentarily compromised, her next work, The Big Four, was a haphazard, rushed affair, regarded as one of her weakest efforts.
 * Blame the Vespiform for that.
 * Dawson Casting: In-universe example:
 * Death in the Clouds: Her 1935 novel of that title is the Trope Namer.
 * Did Not Do the Research / Newer Than They Think: At least two of the novels' presentations in early-2000s British partwork The Agatha Christie Collection. In the magazine accompanying Why Didn't They Ask Evans?, Bobby Jones accompanying his picnic lunch with a bottle of beer he bought on the way (in 1930s Wales) was illustrated with a bottle of Greene King Abbot Ale -- which didn't exist until the 1950s, and was unknown outside Hertfordshire until the 1970s. Both the magazine and the book of Cards on the Table had a poker hand as their front-cover illustration. (The novel is about bridge, to the point where the way bridge is played is essential to the structure of the novel.)
 * Death In The Clouds has a blowpipe a few inches long hidden under a seat. In Mrs McGinty's Dead, Ariadne Oliver says that she wrote a similar scene, and someone wrote to her complaining that blowpipes are actually four feet long.
 * Dispense with the Pleasantries: Iverted in The Pale Horse where Mr. Bradley is shocked at Mark Easterbrook dispensing with the pleasantries.
 * Does This Remind You of Anything?: In Hallowe'en Party, Ariadne mentions that she likes apples. One of the teenage boys replies that "It would be more fun if they were melons. They're so juicy. Think of the mess it would make."
 * The Dog Was the Mastermind: In Crooked House, the murderer turns out to be.
 * Driven to Suicide: Multiple variations. See the trope page for a list.
 * The Dutiful Son: sometimes appears in Big Screwed-Up Family situations.
 * Yahmose, the eldest son in Death Comes as the End.
 * Percival, the eldest son in A Pocket Full of Rye.
 * Richard Abernathie, whose funeral is the catalyst for the events in After the Funeral.
 * Eagle Land: As an rather old-fashioned British subject, it should be no surprise that her depictions of Americans in her works were just a little... off. In fact, you pick up early on that if one of her characters is American, Canadian or Australian, or is an British subject who spent any significant time there, that person is either a) the Asshole Victim, b) the killer or c) if not the killer, than a weak criminal type anyways. And of course, there's the case where everyone has ties to America; they all can't have done it, right?
 * Americans, however, are anything but singled out in her work when it comes to uncomplimentary depictions of human beings, whom Agatha Christie (and many of her characters) believed are basically demons in general regardless of origin.
 * Enfant Terrible:
 * is referred to as a grown-up version of this in Hickory Dickory Dock.
 * Everyone Is a Suspect: One of the central tenets of Christie's body of work. In most of her books, it truly feels that any of the characters could be guilty.
 * is arguably the Trope Maker.
 * Everybody Did It: She wrote the Trope Maker for this one too.
 * Expy: After noting how much she enjoyed writing the gossipy spinster Caroline Sheppard in The Murder of Roger Ackroyd, Christie decided to revamp this character into someone who would become a fixture in her work -- Miss Jane Marple.
 * Bobby Jones and Frankie Derwent of Why Didn't They Ask Evans are expies of Tommy and Tuppence. The ITV productions lampshaded this by having both sets of characters played by the same two actors.
 * Author Avatar Ariadne Oliver's most popular character, Sven Hjerson, is a thinly-disguised expy of Poirot.
 * False Crucible: Parker Pyne seems fond of these.
 * Fate Drives Us Together: William Smith and Christina Grant in Murder on the Nile where he continuously courts her and at last asks to marry her. She refuses at first but it is hinted and later revealed that they do get married.
 * For the Evulz: motivation in Curtain.
 * Framing the Guilty Party: In Towards Zero, it becomes apparent quite early on that is being framed for the murder of Lady Tressilian. However,  is actually the killer, and the false clues were planted by himself to make it appear that.
 * also does a frame job on himself, albeit for different reasons. sets out a bunch of false clues incriminating himself in the hopes that
 * in Hickory Dickory Dock does what is called "double-bluffing".
 * in Lord Edgeware Dies/Thirteen at Dinner Poirot sees through that though...
 * Funny Foreigner
 * Genre Savvy: Take a shot every time someone compares the current situation to a mystery novel, or even rules out a possibility based on its likelihood in fiction.
 * Genteel Interbellum Setting: The former Trope Namer. Despite this, Christie did make an effort to have her novels keep up with the changing times, with varying degrees of success.
 * Glass-Shattering Sound: The key to the murderer's plan in "The Face of Helen".
 * Golf Clubbing: A golf club is the murder weapon in Spider's Web.
 * Subverted in Towards Zero.
 * Happily-Failed Suicide: MacWhirter in Towards Zero.
 * He Knows Too Much: The surest way for an Agatha Christie character to sign his own death warrant is by attempting to blackmail a killer. of One, Two, Buckle My Shoe and  of Death on the Nile learned this the hard way.
 * Tommy and Tuppence were called in to identify N or M after an intelligence agent had been killed in a fake accident because he was getting too close.
 * Also goes for anyone who didn't know that they knew anything significant (, or who didn't know the whole story but knew something vital . Basically, if you're in an Agatha Christie novel, you'd better hope and pray that you either don't have a major part, don't find anything out, aren't confided to by anyone; or if you do find something out, you know how to keep your mouth shut.
 * Heroic Wannabe: William Smith in Murder on the Nile (Death on the Nile play counterpart), constantly trying to win the heart of Christina Grant.
 * He Who Fights Monsters: Curtain
 * Hot Guys Are Bastards : very, very much. The more attractive a man is, the more his appearance departs from the stuffy, military-ish rough and conservative Englishman, the more immoral he is. Attractive men will be suspected immediately, will usually remind the detectives of other handsome killers they've met, and if they're not the killers, they are likely to be accomplices, blackmailers or withholding evidence because they've acquired it while doing something immoral. Plus, with just a few exceptions, any affection of a handsome man for a woman is false, usually motivated by money.
 * Possibly a case of Write Who You Know. Christie's first husband was a man like this; the marriage ended very badly.
 * Identical Stranger: In "The Case of the Rich Woman", the title character apparently has a doppelganger who is a poor servant girl. The truth is rather more complicated.
 * Incriminating Indifference: Subverted in Hickory Dickory Dock., after   is found dead, is incredibly upset, and because of this, the police say that he can't be the killer. Poirot points out that his tears were indeed genuine, and probably more so because
 * Also subverted in the Miss Marple short story "Tape-Measure Murder." The victim's husband doesn't grieve publicly because he believes in the virtue of Stoicism, causing everyone in the village to believe him guilty. Miss Marple is the only one who thinks he's innocent, because he reminds her of an uncle who was also a Stoic.
 * The Informant: After her criminal activities are revealed,  from Hickory Dickory Dock tells Poirot everything because
 * Inspector Lestrade: In Hercule Poirot novels, Inspector Japp or Captain Hastings. Inspector Craddock sometimes served this role in the Marple books.
 * The character of Giraud, in the Poirot book Murder on the Links, is a parody of this type.
 * Late Arrival Spoiler: Christie's novels occasionally revealed the solutions of previous works, a habit which vexed her publishers. For instance, in Cards on the Table, Poirot makes a reference to the solution to Murder on the Orient Express. The reference is very subtle, but enough to spoil it for someone who has not yet read that novel. Even worse, in Dumb Witness, Poirot casually mentions the names of the guilty parties from four previous novels.
 * One of the characters in The Pale Horse is one of the suspects from Cards on the Table. If you read the former first, you'll know he can't be the guilty party in the latter. Which wouldn't be such a big deal if it weren't for the fact that Cards on the Table was a subversion of Everyone Is a Suspect where four, and only four, suspects could've committed the murder (and the murderer is one of the four). If you read The Pale Horse first, then you only have three suspects.
 * Also catches you out if you only watch the ITV film of Cards on the Table and don't read the book, as the relationships end up somewhat different (too long to explain here, but suffice to make this look like Canon Discontinuity.)
 * Little Old Lady Investigates: Miss Marple.
 * Long Runner: The Mousetrap is running continously on the West End since 1952.
 * Love Hurts: A trope that became a favourite of Agatha's after her divorce from her first husband. When love wasn't driving a character to commit murder, it was guaranteed a broken heart from one side or the other. Only a few pairings survived amidst the body counts and broken hearts.
 * Love Makes You Evil: Oy. To list all examples would be ludicrous, but Death on the Nile in particular
 * Maiden Aunt: Miss Marple
 * Market-Based Title: Several of Christie's novels had their titles changed for their US editions. Some of the changes made sense (US readers wouldn't know what a mews was, so the collection Murder in the Mews was titled Dead Man's Mirror after a different story in the collection), while others seem superfluous (Murder on the Orient Express was changed to Murder in the Calais Coach). The editions currently in print have restored the original British titles.
 * In the case of Murder on the Orient Express, there was a real reason: a mystery novel by the title of Orient Express had come out in the US that same year.
 * Mary Sue: In-Universe, several short stories have the main characters compare themselves to the iron-jawed supermen/wish they could have the beautiful heroines of the cheap novels they read. At the end, they recognize them for the fantasies that they are, and live happier lives for it.
 * The Matchmaker: Both Hercule Poirot and Miss Marple display a tendency at times to play matchmaker in the lives of two lovers who need to be brought together during their investigations.
 * Maybe Magic, Maybe Mundane: The stories involving "the mysterious Mr. Quin", who has a knack for showing up just when something is about to happen, and of saying or doing just the right thing at just the right moment to nudge events in the direction of a happy conclusion. It's heavily implied that he's something other than human, but he never does anything unambiguously supernatural.
 * Meaningful Name: Mr. Harley Quin
 * Meta Twist
 * The Mole: N or M
 * Mr. Exposition: Mr. Satterthwaite has a talent for describing the backstory lucidly and with the occasional poetic touch, and is frequently called on to exercise it. Played with a bit in that this is also his main detective talent; in the course of describing the situation to another character (and to the audience), he will often notice a detail or correlation of details that points to the solution.
 * Murder by Mistake: Subverted more often than not. Most of the time, the victim is the person that the murderer intended to kill, even if it appears otherwise.
 * Played straight in
 * Murder-Suicide: A common resolution.
 * My Beloved Smother: Mrs. Boynton in Appointment With Death is a nigh-perfect example, bleeding over into Evil Matriarch.
 * Mystery Magnet: Again, both Poirot and Marple. Lampshaded in "Dead Man's Mirror" when Major Riddle remarks that with Poirot on the scene, any apparent suicide WOULD be murder.
 * Mystery Writer Detective: Ariadne Oliver
 * Name's the Same : The protagonist of "The Rajah's Emerald" is named James Bond. No connection to Ian Fleming's famous character, who would not make his print debut for another 27 years.
 * Why Didn't They Ask Evans? starts with Bobby Jones playing golf... and very shortly goes on to say that this is not the famous (at the time) pro golfer, but just the vicar's son who happens to have the same (fairly common) name.
 * Never Found the Body
 * Never Trust a Title:
 * Night Swim Equals Death: One of the victims in A Caribbean Mystery falls foul of the killer while swimming at night.
 * Nobody Over 50 Is Gay: Miss Hinchliffe and Miss Murgatroyd in A Murder is Announced, according to a discussion on the Golden Age Mysteries forum.
 * No Export for You: Inverted. The novella "Three Blind Mice", written for the American market, has never been published in Christie's native England. This is because it's the basis for the long-running play The Mousetrap, and it is feared that publishing the story in England -- and making the ending widely known -- would hurt play attendance. Christie's will even states that the text of the play can't be published in the UK until it stops running.
 * Except that it has been published in the UK, as part of the The Agatha Christie Collection partwork.
 * Not Allowed to Grow Up: Inverted with Tommy and Tuppence who are the only Christie characters who are shown to age over time from novel to novel that they appear in. They are young lovers when they first appear, but in their last appearance they are shown as a Grow Old with Me elderly couple.
 * Obfuscating Stupidity: A favored tactic of Poirot.
 * Omniscient Morality License: "Are you happy? If not, consult Mr. Parker Pyne" -- who will probably lie to you, and on odd occasions may deliberately expose you to physical danger, but you will end up happy. His staff occasionally question his methods, but he's the expert on human nature, so there's not much they can do once he assures them that it's all for the best. (This would be easier to take if there weren't that one story where the twist ending is that Parker Pyne is after all capable of getting it horribly wrong.) It's probably meant to be covered by Rule of Funny.
 * On the other hand his clients ARE paying for results - and they get exactly what they asked for.
 * Patchwork Story: The Big Four was originally a series of short stories that were published in The Sketch before being converted into a novel.
 * Path of Inspiration: The Labors of Hercules: The Flock of Geryon
 * Combines with Mushroom Samba: one of the protagonists infiltrating the cult has what she believes to be a genuine religious experience; it turns out later that one of the cult's rituals involves .
 * Play Name Change: In the play rendition of Death on the Nile known as Murder on the Nile, there are significantly fewer characters than in the book counterpart. Names of some characters have also been changed:
 * Marie Van Schuyler and Mrs. Allerton merge into the characer Helen ffoliot-ffoulkes.
 * Miss Bowers and Cornelia Robson merge into the character Christina Grant.
 * Mr. Fanthrop and Mr. Ferguson merge into the character William Smith.
 * Hercule Poirot, Colonel Race, and Andrew Pennington merge into the character Canon Ambrose Pennefather.
 * Simon Doyle's name changes to Simon Mostyn.
 * Linnet Ridgeway's name changes to Kay Ridgeway.
 * Jacqueline de Bellefort's name changes to Jacqueline de Severac.
 * Louise's name isn't changed although her last name is never mentioned.
 * Characters taken out completely include:
 * Salome and Rosalie Otterbourne
 * Tim Allerton
 * Fleetwood
 * Joanna Sutherwood
 * Lord Windelsham
 * Poirot Speak: Trope Namer and codifier.
 * Poisoned Chalice Switcheroo:
 * Put on a Bus: After realizing that Poirot didn't really need a Watson-type character, she quickly married off Captain Hastings and had him move to Argentina (although he periodically returned for more adventures with Poirot).
 * Rear Window Witness: 4:50 from Paddington
 * Recursive Canon: In A Body in the Library, a character listing some mystery novel authors mention Agatha Christie herself.
 * Red Right Hand: in Crooked House.
 * Rescue Romance: "The Adventure of the Discontented Soldier" revolves around one being staged to bring two people together, in such a way that neither the rescuer nor the rescuee realises it was staged.
 * Revised Ending: Christie changed the endings of at least two of her novels when adapting them for the stage.
 * Same Face, Different Name: Christie also wrote six romance novels under the name Mary Westmacott.
 * Serial Killer Killer: "U.N. Owen" in And Then There Were None turns out to be a proto-Dexter.
 * Shout-Out: Partners In Crime is basically one big tribute/parody of the other famous mystery authors of the day.
 * Shown Their Work: Christie was an expert on poisons and how they worked, and she never missed an opportunity to show this knowledge off.
 * Sliding Scale of Anthropomorphism: There are a couple of times in the books when the narrative switches to a dog's point of view, with the dogs coming somewhat close to the "Intellectual Animal" point - examples include Bob from Dumb Witness and half a page from Towards Zero.
 * Something Completely Different: Death Comes As The End, a murder mystery set in Ancient Egypt.
 * Spousal Privilege: A key plot point in Witness for the Prosecution.
 * Stealth Hi Bye: The title character in the short story collection The Mysterious Mr. Quin
 * Stopped Clock: A prominent clue in "At the Crossroads".
 * Also subverted in at least two Poirot stories, where a smashed watch is found at the scene
 * Strictly Formula: Every Poirot novel has a character at some point say/think 'The man's a mountebank' and is promptly proved wrong. Every Marple novel has someone say/think 'She's gaga' and is promptly proved wrong.
 * Suicide, Not Murder: Played with in the novels, though Never Suicide ultimately wins out 99% of the time. Occasionally one of a series of deaths will turn out to be a suicide, but there is always at least one genuine homicide in each full-length novel. However,.
 * Sympathetic Murderer
 * Take That: In Death in the Clouds, one character (a novelist) says that the Sherlock Holmes stories are overrated and filled with logical fallacies.
 * Taking the Heat
 * Tap on the Head: Multiple instances. One notable example is "The Adventure of the Discontented Solider", in which the protagonist is genuinely knocked unconscious as part of a fake abduction being staged for his benefit; it doesn't seem to have occurred to his helpful abductors that he might end up with a unhelpful subdural haematoma (but fortunately, this being Christie, he doesn't).
 * Ten Little Murder Victims: Trope Namer
 * Theme Naming: Christie was fond of titling her works after nursery rhymes. Novel examples include And Then There Were None; One, Two, Buckle My Shoe; Five Little Pigs; Crooked House; Hickory Dickory Dock; and A Pocket Full of Rye. Short stories include "Sing a Song of Sixpence", "Four and Twenty Blackbirds", "How Does Your Garden Grow", and "Three Blind Mice". Note that each of the first three lines of "Sing a Song of Sixpence" has provided the title of a work.
 * And the novel Postern of Fate and the short story The Gate of Baghdad, both of which titles came from the first quarter of the poem Gates of Damascus by James Elroy Flecker.
 * Third Person Person: Poirot.
 * Thriller on the Express: Murder on the Orient Express is the Trope Namer, but Mystery of the Blue Train is also an example.
 * Tontine: Several of her books rely on them.
 * Too Dumb to Live: Anyone who blackmails a murderer.
 * Twist Ending
 * Unreliable Narrator: . Though technically this narrator never misinforms the reader of anything.
 * The Verse: Although Christie withstood public demands and never put Poirot and Marple in a story together, there was enough Crossover among the lesser characters to show that they both lived in the same world. For instance,
 * A minor character, Mr. Robinson, appeared briefly with each of Poirot and Miss Marple, as well as in Passenger to Frankfurt, which featured neither of them.
 * He also appears in Postern of Fate, with Tommy and Tuppence.
 * The Pale Horse, which does not feature Poirot or Miss Marple, does feature Mr. and Mrs. Dane Calthorp (who had appeared in Miss Marple novel The Moving Finger) along with Ariadne Oliver, who appears in several Poirot novels, and Major Despard, one of the suspects from the Poirot novel Cards on the Table.
 * Speaking of Ariadne Oliver, she first appeared as a supporting character to Parker Pyne, one of Christie's lesser-known detectives; as did another of Poirot's supporting cast, Miss Felicity Lemon.
 * Superintendent Battle of Scotland Yard, another of Christie's lesser-known detectives (Towards Zero, etc.) is a supporting character in the Hercule Poirot novel Cards on the Table and is mentioned in at least one other Hercule Poirot novel (Hercule Poirot's Christmas); his (by Word of God) son appears in The Clocks, another Poirot novel.
 * Colonel Race, who also appears as a supporting character in two novels with Hercule Poirot (Death on the Nile and the aforementioned Cards on the Table), but also in The Man in the Brown Suit and Sparkling Cyanide (which are not Hercule Poirot novels).
 * Another of Christie's lesser-known detectives, the elderly Mr Satterthwaite, collaborates with Poirot in the novel Three Act Tragedy, which ties the supernatural-themed Harley Quin stories into the universe.
 * The Beresfords have clearly heard of Hercule Poirot enough to make jokes about him and pretend to be him while solving a case in Partners in Crime, and in The Secret Adversary they meet  Poirot's friend Inspector Japp
 * The Watson: Captain Hastings in the early Poirot novels. After gradually phasing Hastings out, Christie used a variety of one-shot characters in this role. He was brought back for Curtain.
 * This is sometimes lampshaded. In one story, a girl says something to the effect of, "Dr. Watson, I presume?" when introduced to him and Poirot.
 * Well-Intentioned Extremist: . Understanding he has the capacity for this is part of what makes him
 * Wham! Episode: The Murder of Roger Ackroyd, whose controversial solution not only made Christie a household name, but which completely changed the course of detective fiction.
 * Yandere: So very many. One of her most prominent yandere is Vera Claythorne from And Then There Were None who
 * Another good example would have to be  from Death on the Nile who   And who still manages to be one of the most sympathetic murderers in an Agatha Christie novel.


 * You Said You Would Let Them Go: The murder of Daisy Armstrong in Murder on the Orient Express.