Jerry and Joanna Burton, brother and sister from London society, take a country house in idyllic Lymstock so that Jerry can rest from injuries received in a wartime plane crash. Just as they are getting to know some of the town's rather strange inhabitants, they receive an anonymous letter accusing them of being lovers, instead of siblings. They are told that these anonymous "poison pen" letters have been circulating widely around the town, making various accusations that are unpleasant, but inaccurate. The situation takes an ugly turn when a woman commits suicide after receiving a letter, and the police move in to investigate.
One of only two Christie novels in which the American edition substantially differs in content from the original British (the other is the Poirot novel Three Act Tragedy). The American version cuts out much of the incidental description and character development, focussing more tightly on the mystery.
This work contains examples of:
- Absence of Evidence:
- Mrs Symmington's poison letter was a plant, and poor Agnes figured this out when, in the process of watching for her boyfriend, she realised that nobody had come to the house to deliver mail that day.
- Elsie Holland doesn't receive a letter. Given that she's an obvious target, the lack of such a letter is a clue in itself.
- Abusive Parents:
- Of the emotionally abusive kind. Megan's mother and step-father usually ignore her, and it's observed by Jerry Burton and others that Megan's presence upsets what would have been a traditional nuclear family. It is evident that Megan feels this.
- Emily Barton, Jerry and Joanna's landlady, is the last of five sisters whose mother kept them from ever going out on their own or getting married, while blaming them for this.
- Advertised Extra: Miss Marple herself only has a handful of scenes and doesn't even appear until about the final third of the novel.
- Alliterative Family: Jerry and Joanna Burton, brother and sister.
- Asshole Victim: Jerry has a rather striking Moral Myopia moment when he considers that the current state of affairs required the deaths of Mrs. Symmington and Agnes, and gets over it by thinking that the former was a prudish, neurotic hypochondriac and the latter wasn't really liked by her boyfriend. On the other hand, the first was an emotionally abusive parent to Jerry's fiancee, Megan, and the latter was someone he'd never actually met. This was in response to Miss Barton (a life-long village resident who knew both murder victims well) remarking that "everything really has worked out for the best"!
- Beautiful All Along: Jerry's ongoing frustration at Megan's poor self image and aggressively down-at-heels appearance, combined with her wistful expression as she sees him off to London, results in him 'going mad' and taking her to his sister's stylist in town. The results rather stun them both.
- Blackmail Backfire: As is standard for a Christie novel, an attempt to blackmail the murderer results in the blackmailer being almost murdered. Subverted in that it wasn't a real attempt but a case of Bluffing the Murderer.
- Bluffing the Murderer: Turns out to be the only way to catch the very cunning murderer who has succeeded in framing somebody else. Engineered by Miss Marple with Megan as The Bait.
- Camp Gay: Mr Pye, who is alluded to be gay, is also described as "abnormally feminine," can recognize a makeup brand when seeing it on Joanna's face, and is included by the police as a suspect even though they insist, on experience, that the culprit must be female. Though it isn't.
- Crouching Moron, Hidden Badass: Dr Griffith is bumbling and awkward when faced with Joanna's bold, flirtatious, big-city personality, and his idea of courting is showing her pictures of diseased internal organs. He impresses the hell out of her when, as she has faked interest in medicine, he takes her along on a difficult case.
- Did Not Think This Through: Combined with a near-terminal case of Skewed Priorities. Aimee Griffith decides to use the murderer's poison-pen campaign as a cover for her own poison-pen letter to a romantic rival, reasoning that the murderer will be blamed. (Two people are dead, but sure, now is a great time to work out your petty romantic rivalries.) However, she does not make the next logical conclusion, which is that if anyone finds out she wrote this letter, they will then have a good reason to think she's the murderer. Which is exactly what happens.
- Dissonant Serenity: Referenced when Jerry marvels that Inspector Graves is surprisingly cheerful for an expert in anonymous letters, who has to look into some pretty twisted minds on a regular basis.
- Driving Question: Who is sending these letters? But as Miss Marple points out, this was the wrong question.
- Earn Your Happy Ending: Emily Barton is finally freed from keeping the house her domineering mother had forced her to live in her whole life and goes on a round-the-world cruise, taking Aimée Griffith with her for the ride.
- Fair-Play Whodunnit: It is hinted at and implied a couple of times (though only that... this is Agatha Christie, after all) the first is Jerry's reaction to Elsie Holland herself - he's been absolutely oblivious to the fairer sex, to Joanna's disbelief and slight worry. But one look at Elsie (described more or less as the physical embodiment of Helen of Troy, but minus the charisma) and he's shocked back to life. But she's a live-in nanny... for a man who seems completely oblivious to this. More importantly - as the Inspector lampshades and Miss Marple states in her summation - this beautiful, single girl doesn't get an anonymous letter (and in the normal run of this sort of thing, she should have received one of the very first). The only reason for this is that the letter writer cares for her deeply. Given that Elsie is unattached, what reason would a man have for hiding his interest in her, other than he's married? And the nearest available married man is her employer.
- First-Person Peripheral Narrator: Jerry Burton.
- He Knows Too Much: Agnes was murdered because she figured out that no mail had been delivered on the day on which Mrs. Symmington was supposed to have received the poison pen letter that allegedly prompted her to commit suicide.
- I Choose to Stay: Jerry and Joanna came to Lymstock so that Jerry can recuperate from his injuries. The initial plan was to stay only for 6 months, but both eventually marry and settle down in the village.
- I Want My Beloved to Be Fashionable: After Megan remarks that she doesn't care about her appearance because she could never be good looking anyway, Jerry spontaneously brings her to London for a makeover. Afterwards, he realizes that he did it because he's in love with her.
- Jerkass: Aimee Griffith isn't a very likable person. She goes on about how the letter writer must have hit onto something about Megan's mother while scoffing at how a letter she received certainly couldn't be taken seriously. She harshly mocks the idea of anyone (even great thinkers) being idle and throws around claims of misogyny when she's questioned. She makes a snide, racist comment about the Chinese in response to a drawing Jerry made of a Chinese man. After the deaths and the police investigation, she cheerfully comments about how nice the excitement is. She bullies Megan into moving back to her stepfather's house (where she's miserable) just in order to prevent an air of scandal attaching itself to her stepfather (like Aimee feels it would if he was left alone in the house with Elsie). She sends a nasty anonymous letter of her own to Elsie.
- Literary Allusion Title: The title comes from Edward FitzGerald's translation of "The Rubáiyát of Omar Khayyám":The Moving Finger writes, and having writ
Moves on: nor all thy Piety nor Wit
Shall lure it back to cancel half a Line,
Nor all thy Tears wash out a Word of it.
- Love Makes You Evil: This story has both a male and a female example: Mr. Symmington, and, to a much lesser extent, Aimee Griffith. The former murders his wife in order to be able to marry Elsie Holland, while Miss Griffith is driven by her love of Mr. Symmington to type a foul letter to Elsie in order to drive her away.
- Makeover Fairy: Having promised Megan a makeover, Jerry hands off the details to an expert: his sister's stylist "Mirotin".
- Marry the Nanny: Aimee Griffith thinks this will happen with Elsie Holland and Mr. Symmington, because Elsie is essentially running the domestic side of the house in the wake of Mrs. Symmington's death (also, she's gorgeous) and he'll come to rely on her so much he can't help but marry her. As Aimee has been desperately in love with Symmington for years, she writes an anonymous letter to Elsie accusing her of this. And then it turns out Mr Symmington has been secretly in love with Elsie the whole time, and that he killed his wife in order to marry her.
- Never One Murder: The murderer is caught on his third attempt - fortunately in time. Poor Agnes.
- Never Suicide: Mrs. Symmington commits suicide after receiving a poison pen letter accusing her of adultery. Actually, she was murdered.
- Non-Indicative Name: As Jerry points out, no one really likes Aimée (French for "Loved") Griffith. Especially not Symmington, who pins the murder of Agnes on her despite her carrying a torch for him for years.
- Noodle Incident: in the latter half the of the book, Mrs Dane Calthrop tells Jerry that she's bringing in an expert on murder: enter Miss Marple. But while Reverend and Mrs Calthrop also appear in The Pale Horse, Miss Marple doesn't. So how does Mrs Calthrop know Miss Marple and what she can do? This is especially peculiar, because in all her other novels and short stories, it's very clearly stated how Miss Marple was introduced to all her cases outside St Mary Mead; it's usually by one of her army of godchildren, (who all call her Aunt Jane) someone she knows from a previous case, or her nephew Raymond takes action to put her in the right place or knows someone involved.
- Nothing Exciting Ever Happens Here: Jerry observes that he moved to the town due to this reason, then all the letters started.
- Ripped from the Headlines: In story. Mr. Symmington got the idea of poison pen letters from a couple of other publicized cases, as a way to make his wife's murder look like suicide.
- She Cleans Up Nicely: Megan can't believe how attractive she can look with a little effort. Jerry recognizes that much of the transformation is due to her improved self-image.
- Single Sex Offspring: Emily Barton, Jerry and Joanna's landlady, is the last of five sisters.
- Stating the Simple Solution: Miss Marple asks a very simple question: who cares who's writing the letters, what has actually happened? She says they should focus on the tangible events and work back from there, rather than trying to untangle who wrote what or whether any of the allegations in the letters are true. The first real happening is Mrs. Symmington's death, and who would want her dead? The husband who wants to marry the beautiful nanny without the stigma of divorce. The letters are a smokescreen.
- The Unfavorite: Megan's mother and step-father have children of their own, and her parents clearly prefer them over her. Jerry is disgusted to realize that Mr. Symmington pays no attention to Megan unless she's right in front of him, and thinks that this might be even worse than Symmington actively disliking her—at least in that case he would see her.
- The 'Verse: Reverend and Mrs Dane Calthrop also appear in another Agatha Christie novel, The Pale Horse, which also features Hercule Poirot's companion Ariadne Oliver in a minor role.
- What Happened to the Mouse?: After Megan's mother is murdered and her stepfather is arrested for the crime, no mention is made of who would take care of her two young half-brothers. It is mentioned in-story that she's not quite 21 yet, and is not yet married. By the standards of the time and place, she might not have been deemed a suitable guardian, and custody might have gone to an aunt or uncle of the boys. Either way, we never find out.
- Womanchild: Megan is in her early twenties but gives the impression of still being a teenager, in large part due to her mother and stepfather making no effort to help her grow.
- Worthy Opponent: Downplayed, but in The Summation, Miss Marple says more than once that the killer (and their plan) was very clever.
- Wounded Gazelle Gambit: Discussed. When the characters wonder if Elsie is sending the letters because she's the only woman who hasn't gotten one, Graves explains that it's actually a mark in favor of her innocence, because in poison-pen cases the culprits almost always send themselves something vile to throw off suspicion and soak up the sympathy.