Summary
Two months pass before John is tried for the murder of his stepmother, Emily Inglethorp. Hastings reports that Mary Cavendish never once accepts John's guilt and is a tireless advocate on his behalf. When Hastings points this out, Poirot remarks that Mary is "of those women who show at their best in adversity" and also labels her as "an unusually jealous woman" (180). Hastings is surprised to hear this assessment, especially after Mary told him, a few months prior, that she planned to leave John and that she never loved him. Poirot explains to Hastings that he, Poirot, must appear to be working for John and on behalf of the defense at all times while looking for the final "missing link" in his chain that will ultimately lead him to be able to indict, without a doubt, the murderer of Emily Inglethorp. The trial takes place in London, and Mary rents a house in Kensington where Poirot stays with them to continue his investigation. Hastings secures a job at the War Office in the city and so is able to keep abreast of the goings-on. Hastings gives a comprehensive account of the trial.
Witnesses are cross-examined brutally by the prosecutor and the defense. The prosecution succinctly relates the narrative that John Cavendish was wrapped up in an extra-marital affair with Mrs. Raikes, a neighboring farmer's wife, and when Emily Inglethorp confronted him about it, he resolved to poison her and blame her husband, of whom he was jealous and covetous of his inheritance of Emily's fortune and Styles Court. The prosecution also maintains that John Cavendish burned the will that Emily Inglethorp drew up after her argument with him. The defense, instead of proving John didn't commit the murder, endeavors to demonstrate that there is just as much if not more evidence against Lawrence Cavendish than there is against his brother, John. The defense's strategy is to sow confusion and reasonable doubt in the minds of the jurors, and it does so by showing that Lawrence stands to inherit Styles Court and John's portion of the inheritance if John is convicted. The defense also recounts that Lawrence handled a bottle of strychnine at the dispensary while visiting Cynthia.
The defense also rightfully calls into question new pieces of dubious evidence. The first is a receipt for a black beard from a costumery company postmarked to Lawrence Cavendish, produced by Eve Howard, who claims she found it on top of John's wardrobe. The other piece of evidence is a long piece of blotting paper with the imprint of a fragment of a sentence that clearly shows that the burned will was written in favor of Alfred Inglethorp. The blotting paper was found in John's wardrobe underneath winter clothes. The defense points out that it doesn't make sense that John would keep this evidence in his wardrobe for a full week after the crime was committed. The wardrobe wasn't locked, and his room is quite accessible to others. The defense succeeds in sowing confusion and doubt.
When the defense calls John to the stand, he produces a letter that explains his lack of an alibi; on the day that the strychnine was purchased, John received a note laden with threats of blackmail if he did not meet at Marston's Spinney at a certain time in the afternoon. When John arrived at the spot, he waited for a while before leaving because no one showed up. The defense proposes that the note was obviously an effort on the actual culprit to deny John an alibi while they were purchasing the poison disguised as Alfred Inglethorp. In closing arguments, John also vehemently rejects the defense's strategy of trying to shunt blame to his brother, Lawrence, and maintains that he thinks his brother is just as innocent as he is. The prosecution tries to accuse John of perjuring himself, but he maintains his innocence.
Back at Mary's house in Kensington, Hastings debriefs with Poirot about the trial. Poirot is beside himself because he has still failed to find the missing link in his case. He starts building a house of cards in his bedroom. Hastings is rather surprised that Poirot does this, but Poirot explains that it is a way of focusing and steadying his mind. His hands shake when he is angry or distressed, and building houses of cards force him to steady his hands. Hastings says that he's only seen Poirot angry once, when he saw that the despatch case had been forced open. When Hastings says this, Poirot flies out of the room, claiming that he has thought of a huge, case-cracking idea from Hastings' off-the-cuff statement about the lock on the despatch case. Poirot runs out into the street in search of a garage with no explanation as to why.
Poirot returns to the Kensington house late in the afternoon the day after he abruptly departed. He gathers everyone in the parlor of the house—the Cavendishes, Cynthia, Dorcas, Alfred, Eve, and the other Styles staff—and unfolds the narrative that he was able to construct after figuring out the missing link to the case. Poirot explains that the fragment of green material had to have come from Mary Cavendish's green armlet; Mary entered Emily's room looking for a letter that she thought concerned John Cavendish's affair with Mrs. Raikes. The letter in question, however, concerned another affair altogether. Emily found the letter while she was looking for stamps in Alfred's desk. He does not immediately reveal the contents of the letter, but first explains how Cynthia was able to sleep through Mary traipsing through her room to get to Emily's room.
Poirot analyzed Cynthia's coffee cup from the night of the tragedy and found traces of a non-lethal narcotic that induces deep sleep. He found the same narcotic in Emily Inglethorp's cocoa, and explains that it was administered by Mary to keep them both asleep while she snuck through their rooms to obtain the letter. Mary readily admits to dosing their drinks. She tells the room how frightened she was when she heard that Emily died of poisoning, because she thought she was responsible. In fact, the sleeping draught is what accounts for the delayed effects of the strychnine. Poirot also explains that the person who burned Emily's newly revised will was Emily herself; why else, he asks, would she order a fire to be made in her room on the hottest day of the year?
Poirot then explains that the strychnine that killed Emily Inglethorp was the very same strychnine prescribed to her by Dr. Watkins—Poirot reads an entry from a medical journal explaining that introducing bromide powders into a solution of strychnine hydrochloride will cause the strychnine to precipitate out and sink to the bottom of the solution, causing the patient to ingest all of the strychnine at once in their last dose. Poirot goes on to say that the fatal dose was meant to be taken twenty-four hours prior to when it was, which led to the smoking gun letter that Poirot has in his possession, written to none other than Evelyn Howard from Alfred Inglethorp. In the letter, Alfred assures Evelyn that the deed will be done posthaste and compliments her for her idea to introduce the bromide powders, calling it a "stroke of genius" (213). When Poirot reads the incriminating letter, Alfred jumps up and lunges at him, but Poirot feints and Alfred falls.
After the dust settles in the days that follow, Poirot and Hastings find themselves alone again, and Hastings is still mad at Poirot for keeping him in the dark. Poirot insists that he did no such thing, and that, in fact, he supplied Hastings with all the clues he could possibly have needed to crack the case himself. He claims to have refrained from telling Hastings his thoughts outright for fear that Hastings' "transparent countenance" (215) would have given everything away to Alfred. Hastings feels that Poirot doesn't give him enough credit. Poirot then goes through and explains all of the little innuendos and subtle language he used throughout the investigation to attempt to lead Hastings along the right path, but Hastings concedes that most of the clues went right over his head.
Poirot then goes on to explain the minutiae of how Alfred and Evelyn pulled off the murder, and how the evidence at many points pointed to other culprits. Poirot says that at one point, Cynthia seemed the most likely culprit, and explains that Lawrence covered for her by breaking the coffee cup in Emily's room (having suspected it was poisoned) and also by claiming that the door from Cynthia's room to Emily's room was bolted on the night of the tragedy when it was not. Poirot maintains, much to Hastings' surprise, that Cynthia and Lawrence are in love with one another. Poirot also explains that he could have cleared John's name and avoided his trial, but if he did, he would have risked letting Alfred and Eve off; Poirot also claims that he was sure the distress and dire straits of the trial would bring John and Mary back together, and that that was reason enough to let John stand trial. The novel ends with Cynthia and Lawrence coming in to thank Hastings and Poirot. Poirot notices that Hastings looks glum and guesses correctly that it is because both of the women Hastings developed romantic interests in have ended up with a Cavendish brother. The book ends with Poirot suggesting that the two of them will work together again, and that Hastings may find love yet.
Analysis
In the 2012 edition of Agatha Christie's debut novel, The Mysterious Affair at Styles, John Curran, a Christie scholar, introduces the book and explains the appended "original ending." When Christie published the novel in 1921, her editor insisted that she revise the original ending so that Poirot did not make his grand explanations at the courthouse, but rather in a drawing room with all of the suspects present. The insistence was evidently in the name of realism—the first readers and editors had their doubts that a private detective would be allowed to explain his circuitous findings in the heat of a live trial—but what was proposed as a practical edit ended up giving rise to what Curran calls "a half-century of drawing-room elucidations stage-managed by Poirot" (xvi). Not only did this denouement scene set a precedent for Christie's own work, but its influence and emulation is also seen in almost every procedural detective drama on television in the last century.
The manner in which Poirot reveals the "actual" narrative of what happened on the night of the tragedy occurs in two stages. The first stage is the more public one, in which everyone is gathered in the drawing-room. Here, Poirot provides the broad strokes of what happened, new pieces of major evidence, and ultimately an indictment of the guilty parties—in this case, Alfred Inglethorp and Evelyn Howard. The second stage occurs a few days later, in private, with Hastings. These elucidations are clearly for the reader, and they emphasize Hastings' role as a surrogate of the reader. Hastings feels fooled, toyed with, and deceived by his friend Poirot, but Poirot maintains that he didn't deceive Hastings, he merely "permitted [him] to deceive [him]self" (215). Poirot then proceeds with the second-order explanations, in which Christie shows, through Poirot, how she uses vague language and sleight-of-hand ambiguity to misdirect the reader. Poirot is established early on as a wiz of a detective, and at one point during the trial, Hastings describes him as a "true prophet" (183). Therefore, the reader, like Hastings, tends to blindly follow Poirot's lead—however, Christie has Poirot use intentionally ambiguous language, so even when we place all of our trust in him, we can never be truly confident that we know where he's leading us. Following Poirot through a case is like following someone who drives too fast and isn't concerned with whether the person following them is able to keep up. Poirot weaves through the traffic of clues and inconsistencies and takes hairpin turns to adapt to circumstances, leaving the reader, and Hastings, several paces behind.
On the other hand, much of Poirot's misdirection seems like intentional vagueness and obfuscation. For example, regarding John Cavendish's guilt, Poirot says, "Did I ever say to you that I believed John Cavendish guilty? Did I not, on the contrary, tell you that he would almost certainly be acquitted? ... And did I not immediately afterward speak of the difficulty of bringing the murderer to justice? Was it not plain to you that I was speaking of two entirely different persons?" To which Hastings, quite incredulously, responds, "No ... it was not plain to me!" (216). Hastings' tone almost anticipates the reader's outrage from Christie's point of view. Poirot essentially gaslights Hastings into believing that he wasn't intentionally deceiving him, when Poirot's omissions are clearly intentionally misleading. Poirot chalks it up to semantics and misunderstanding, but the subtle linguistic trickery further underscores his impishness and prepares the reader to take everything Poirot says with a grain of salt in future installments, because what he says can clearly not be interpreted at face value. Poirot can move from one sentence to another, and where in normal conversation one would assume the subjects of his sentences would remain the same, Poirot will claim that he was "clearly" talking about two different people all along. By the final line of the novel, it is no surprise that Christie had signed a six-book contract when she published Styles, because it promises more sleuthing adventures with Poirot and Hastings; no doubt Poirot will have a more difficult time fooling his gullible friend on their second case.
