Inheritance
The basis of the novel's conflict, even before Emily is killed, is competition over Styles Court and the Cavendish fortune. Hastings points out in his very first encounter with John Cavendish, immediately after he describes being invited to Styles, that Emily Inglethorp is not John and Lawrence's biological mother; she is, rather, their step-mother. However, Hastings also clarifies that "they were so young at the time of their father's remarriage that they always thought of her as their own mother." Though, Hastings also recalls that John's father "Had been completely under his wife's ascendancy, so much so that, on dying, he left the place to her for her lifetime, as well as the larger part of his income; an arrangement," Hastings posits, "that was distinctly unfair to his two sons" (2). By introducing this complex web of relationships, Christie deftly constructs the family fortune as a thing to which no one has a perfect claim. Each character—John, Lawrence, Emily, and even Cynthia and Alfred Inglethorp— has a different plausible reason why the fortune should be theirs, and Emily's status as "step" mother complicates her original claim to the fortune.
Much of the confusion surrounding the destroyed will stems from the characters' confessed confusion over the actual laws surrounding wills. At one point, Hastings admits to Poirot that "all these wills are very confusing," (86) and as an explanation as to why Emily even drew up a new will in the first place, Hastings offers a possible, if condescending, explanation: "She was an old lady, and might possibly have forgotten the former one; or—this seemed to him more likely—she may have had an idea that it was revoked by her marriage, as there had been some conversation on the subject. Ladies were not always very well versed in legal knowledge" (185). Then, during the trial of John Cavendish, one of the most inflammatory questions posed by the defense lawyer was posed to Lawrence Cavendish, asking him who stood to inherit the family fortune if John were arrested. The answer, of course, is Lawrence Cavendish, the suggestion being that he somehow framed his brother to ensure his receipt of the fortune.
The question of inheritance, estate, and shared fortunes are thus central to the plot and to the web of character relationships therein.
Merrie Olde England
Merrie England is a hegemonic concept of English society that romanticizes a mythic, pre-industrial, feudal way of life. The setting of The Mysterious Affair at Styles implicates itself in this problematic, nostalgic vision of a "utopian" society that never was. Christie describes Hastings' arrival at the village of Styles St. Mary: "I descended from the train at Styles St. Mary, an absurd little station, with no apparent reason for existence, perched up in the midst of green fields and country lanes" (4). The people in Styles Court are involved in industrial society in the abstract; their daily routines are altered for the sake of contributing to "the war effort," and Hastings, himself, was injured at war and for that reason finds himself in Styles in the first place. Styles represents, especially for Hastings, an escape from industrial society and a way to connect with the conservative idyll of the pastoral.
Christie distills much of what the novel has to say along the trajectory of the Merrie England concept into the character of Dorcas, Emily's longtime, loyal, faithful maidservant. Hastings is charmed and delighted by Dorcas's undying loyalty to the Cavendish family and what he sees as her "charming" brand of xenophobia. When Hastings asks Dorcas about Poirot, she responds, "a very nice gentleman he is, sir. And quite a different class from them two detectives from London, what goes prying about, and asking questions. I don’t hold with foreigners as a rule, but from what the newspapers say I make out as how these brave Belges isn’t the ordinary run of foreigners, and certainly he’s a most polite spoken gentleman." Upon hearing her say this, Hastings, charmed, narrates, "Dear old Dorcas! As she stood there, with her honest face upturned to mine, I thought what a fine specimen she was of the old-fashioned servant that is so fast dying out" (136). A few elements of what Hastings says here reinforce the hegemonic order of the mythic society evoked through the Merrie England lens. For one, Hastings' language objectifies Dorcas, referring to her as a "specimen," and furthermore as a type of person rather than a singular, whole person outside of her profession. To Hastings, Dorcas is, in her essence, a servant. There would be no Dorcas without her employment as Emily Inglethorp's maid. Furthermore, Hastings emphasizes how her "honest face" was "upturned" to his, as in, he is literally looking down on her.
Dorcas's own xenophobia (of course given to her by Christie) upholds the cultural hegemony of feudal lords by making the servant class loyal to the same essentialist ideas of country and class that maintain the concentration of wealth and contribute to Dorcas's own oppression.
Law and Order
At the center of most detective novels is a concept of justice and law and order. Some strange or ingenious crime has been committed, so an exceptional mind is put to the task of figuring out who committed it and how, and bringing the perpetrator to "justice." Poirot has a unique relationship with his "official" counterparts, Detective-Inspector Japp and his partner, Summerhaye, in that they actually like him and defer to him. A common trope of private detective novels is that the P.I. is a nuisance, a "loose canon" who is seen to interfere in the lawful, bureaucratic processes of official law enforcement, and whose contributions to the process of bringing a perpetrator to justice are only begrudgingly recognized, if they are recognized at all. Poirot, on the other hand, seems to delight officials and inspire their utmost respect.
Christie also heavily evokes a legal atmosphere. Three chapters of the novel take place primarily in and around a courthouse, between the initial inquest and the trial of John Cavendish in London. Christie provided somewhat of a roadmap for modern procedural crime dramas, which, once the case is solved, tend to shunt the action into a judge's chamber. But, being a private operator, Poirot isn't hemmed in by the same standards as his official counterparts, which is why he is able to, for example, allow John to sit in jail for three months while he waits for the "missing link" of his case's chain to manifest itself, as opposed to bringing his theories to the police right away. Poirot is able to build a case on his terms, because his investigation isn't regulated in the way that Japp and Summerhaye's investigation is; however, Christie characterizes their mission as a shared one: bringing the murderer to justice.
Indebtedness
Part of Emily Inglethorp's "autocratic personality" (2) is her tendency to keep receipts of her generosity. Evelyn Howard concisely sums up Emily's quid pro quo sensibility when she tells Hastings, after Emily dies, that "she was very generous, but she always wanted a return. She never let people forget what she had done for them—and, that way she missed love" (79). A major point for the prosecution against John during his trial is Emily's generosity. Hastings describes how the prosecution portrays John's relationship to his mother as that of a leech and ungrateful dependent:
The murder, [the prosecutor] said, was a most premeditated and cold-blooded one. It was neither more nor less than the deliberate poisoning of a fond and trusting woman by the stepson to whom she had been more than a mother. Ever since his boyhood, she had supported him. He and his wife had lived at Styles Court in every luxury, surrounded by her care and attention. She had been their kind and generous benefactress. (184)
And when Dorcas recounts the argument she overheard outside of Emily's bedroom the night before her death, she mistakenly thinks Emily was arguing with Alfred. Dorcas reports what she heard Emily say: "How dare you? I have kept you and clothed you and fed you! You owe everything to me! And this is how you repay me! By bringing disgrace upon our name!" (51). The fact that Dorcas could just as well imagine Alfred as the recipient of this tirade as John demonstrates how Emily often saw her relationships with people in terms of what they owe her, and many people owed her. The irony of Evelyn Howard refusing Emily's generosity is that she plans to take everything Emily has by murdering her and running away with her husband, who she hopes will inherit all of Emily's wealth.
Medicine, Toxicology, and Poisoning
It comes as no surprise that Agatha Christie worked at a hospital dispensary while writing The Mysterious Affair at Styles, seeing as nearly half of the main cast of characters have some close tie to the medical community. There is Lawrence Cavendish, who studied to be a physician and even earned his license, but doesn't practice because he's decided to pursue poetry instead. Dr. Bauerstein happens to be an international authority on poisons and toxicology. Dr. Watkins is Emily's personal physician, Cynthia Murdock works, like Christie, at a dispensary compounding medicines, and Evelyn Howard also works at a hospital, and, additionally, is the daughter of a physician. Which is to say, all of these characters are more knowledgeable about chemistry and compounding than the average person, and their knowledge is essential to the plot. In fact, it is Evelyn Howard's intimate knowledge of bromides that allows her to devise such an ingenious plan to kill Emily—the plan is so tidy that it doesn't require her or Alfred to actually introduce any strychnine into Emily's system. Instead, they use her own medications, which contain a trace amount of strychnine, and mix in her bromide powders, which Evelyn knows causes strychnine to precipitate out of solution, and let Emily poison herself. The fact that so many other characters could also have ostensibly devised this plan adds to the suspense and prolongs the mystery.
Infidelity
There isn't a single married couple in The Mysterious Affair at Styles that isn't touched by an extramarital affair. A shocking affair is at the center of the crime in question—Eve Howard's romance with a man for whom she's gone to great lengths to publicly express her disdain, Alfred Inglethorp, to whom she also claims to be a distant cousin. Eve and Alfred pretend to be mortal enemies in a tug of war over Emily's heart and loyalties, when in fact their loyalties belong to one another. Then there is John and Mary's marriage; both of them are carrying on affairs. Mary is romantically involved with Dr. Bauerstein, but any potential love she feels for him is spoiled with the revelation that he's a German spy and was possibly using her for intel. Then, of course, there is John, whose affair with Mrs. Raikes, the wife of a neighboring farmer, is public knowledge. Infidelity is an important component of the novel because the shame of it and the threat of their unfaithful behavior going public puts pressure on the characters and causes them to act in ways that end up incriminating them or obstructing the truth because in order to make the truth known, they would have to admit to carrying on an affair. A prime example of this is John's failure to produce an alibi for the time the strychnine was purchased. Eve and Alfred are able to blackmail John into going to a remote location by writing a note threatening to out his affair with Raikes; they therefore are able to use John's infidelity to try to pin the crime on him, and they almost succeed.
The War Effort
The Mysterious Affair at Styles is lauded for being not only a well-contrived mystery, but also a surprisingly faithful artifact of its setting in its particular time in history—England during the first World War. The novel is certainly not about the war, but the war is a palpable backdrop of the events therein. It is as if the war is in the musculature of the novel, and it is a topic so integrated into the lives and culture of the characters that they speak about it as a matter of course. For one, Hastings fought in the war. In a way, the war is an inciting incident for his narration, because his injuries put him in a convalescent home and are the reason he was granted a month's leave, which he spends at Styles Court.
In addition to Hastings being a veteran of the ongoing war, the notion of "the war effort" on the homefront also pervades the novel. A primary exemplar of Emily Inglethorp's predilection for ostentatious demonstrations of her generosity is her frequent mention of the sacrifices and donations her household is making toward the war effort. They are conserving food and resources in the home (a fairly superficial gesture given the general excess in which she and the Cavendishes live) and she hosts a grand bazaar in Essex to fundraise for the war effort right before her death. When Hastings asks John to catch him up on life at Styles, one of the first things John mentions is how "the war" has increased the number of "societies" of which Emily sits on the boards from hundreds to thousands (3), and one of the first things Emily says to Hastings when he arrives at Styles is that "one must set an example of economy. We are quite a war household," she emphasizes; "nothing is wasted here—every scrap of waste paper, even, is saved and sent away in sacks" (11). Even the red herring of Dr. Bauerstein's arrest is related to the war in that he's arrested on suspicion of conducting espionage for the German government.
