Because The Mysterious Affair at Styles is written as a recollection of previous events, Captain Arthur Hastings’s narration of the novel is full of moments that foreshadow important revelations. These instances begin as early as Chapter 1, when Hastings remarks on his first impression of Alfred Inglethorp in the quote below, foreshadowing Mr. Inglethorp’s status as one of the two antagonists of the novel:
His watchful and attentive manner never varied. From the very first I took a firm and rooted dislike to him, and I flatter myself that my first judgements are usually fairly shrewd.
In Hastings’s own remembrance of the story, he is careful to observe Mr. Inglethorp’s behavior from the moment they meet—and he does not like what he sees. The “watchful and attentive manner” he notices in Mr. Inglethorp is almost preternaturally steady, indicating that the man’s poise and detailed attitude may be subtle signs of his carefully constructed facade. Hastings’s instant dislike of Mr. Inglethorp is perhaps falsely inflated due to this story being the narrator’s own recounting of events (with full knowledge of the murderer’s identity), but nonetheless his feelings towards Mr. Inglethorp hint to the reader that they should not trust the man.
Captain Arthur Hastings and Evelyn Howard’s conversation regarding detective work and the difference between reality and fiction is full of both foreshadowing and situational irony:
“Like a good detective story myself,” remarked Miss Howard. “Lots of nonsense written, though. Criminal discovered in last chapter. Every one dumbfounded. Real crime—you’d know at once.”
“There have been a great number of undiscovered crimes,” I argued.
“Don’t mean the police, but the people that are right in it. The family. You couldn’t really hoodwink them. They’d know.”
In the passage above, Evelyn confidently insists that murder mysteries are unrealistic even if they are entertaining, claiming that in real life crimes are much more easily solved. This assertion is an ironic bit of foreshadowing, as Christie humorously pokes fun at the genre of her own novel. Evelyn’s remarks on the absurdity of the detective story structure—the grand final reveals and “dumbfounded” reactions—lay out the exact sequence of plot events that later happen in Christie’s own novel. Further, Evelyn’s declaration that it would be impossible to effectively “hoodwink” those involved in the story (thereby drawing out the mystery) essentially functions as a dare to the reader, inviting them to be on the lookout for clues. As one of the two villains of the story, along with Alfred Inglethorp, Evelyn’s comment regarding the relative mundanity of real-life crime foreshadows her own involvement in Emily's murder by priming Hastings and the other residents at Styles Court to rely on their first, impulsive instincts.
During an unfortunately ominous conversation about the frequency of undetected acts of poisoning in Chapter 1, Emily Inglethorp uses a simile to express her displeasure with the direction of the group’s subject matter, thereby foreshadowing her imminent death:
Why, Mary, what a gruesome conversation!” cried Mrs. Inglethorp. “It makes me feel as if a goose were walking over my grave. Oh, there’s Cynthia!
Emily’s declaration that Mary and Hastings’s casual discussion of poison and rampant, unpunished murder is deeply prescient. The vivid specificity of her language contributes to the foreshadowing effect of the passage above. Her claim that such lighthearted musings about murder and poison make her feel like a "goose is walking over her grave" signals that she will not last long in this narrative. This simile is functionally equivalent to the phrase "a chill went down my spine." Thus, it conveys Mrs. Inglethorp’s psychological fear and physiological discomfort at the possibility of being poisoned and the distinct threat of that crime’s potential to go undiscovered. This conversation is therefore also an ironic bit of foreshadowing, as Emily meets her own demise by way of poisoning and the culprits responsible for her death are present to hear her express the depth of her negative feelings towards this particular kind of death.
In Chapter 4, Poirot and Hastings discuss Poirot’s investigative methodology. As Poirot outlines his philosophy on proper detective work, he foreshadows the fact that clues to the novel’s murder mystery have already been revealed (and will continue to reveal themselves):
Beware! Peril to the detective who says: ‘It is so small—it does not matter. It will not agree. I will forget it.’ That way lies confusion! Everything matters.
In the quote above, Poirot is fervently insistent as he declares that "everything matters"—every single detail, no matter how small or seemingly insignificant. The cautionary words he imparts are dire in their extremity, as both “Beware!” and “Peril” convey a sense of danger that goes beyond merely making a mistake in one’s work. Poirot’s language reveals the solemnity with which he views his profession—the very reason he is able to feel fulfilled and invigorated by his work is because he demands consistency, deliberation, and utter, undivided attention to every detail. The sheer professionalism Poirot exhibits as he describes his detective style to Hastings in turn reveals the narrator’s own relative inadequacy. Additionally, Poirot makes this statement not only to Hastings, but also to the reader. Throughout the novel, Hastings serves as a stand-in for the reader, detailing his reactions and developing hypotheses as they form in time with each revelation in the murder case. Thus, Poirot’s words of warning may also be taken as a notice for the reader, cautioning patience and careful thought as they watch the novel’s mystery unfold.