Another example of situational irony that imbues "The Open Window" with humor is the effect of this visit on Mr. Nuttel. As he tells Vera and Mrs. Sappleton, he has come to the countryside to soothe his nerves.
"The doctors agree in ordering me complete rest, an absence of mental excitement, and avoidance of anything in the nature of violent physical exercise."
One of the few things we know about Mr. Nuttel is that he is undergoing a nerve cure. And even this information is vague—his ailment seems to be grounded more in the tendency of the leisure class to romanticize frailty and hypochondria than in actual health issues. In line with high society's belief in the restorative force of the countryside, Mr. Nuttel hopes to cure his nerves by leaving the city and going on a rural vacation. Yet, within about thirty minutes at the Sappletons', he bolts off in a "headlong retreat" when he sees the supposed ghosts returning home and presumably shakes up his nerves far more than they had been upon arrival. It is ironic that the very reason Mr. Nuttel finds himself in this place is his pursuit of peace and quiet, because, thanks to Vera's inventive ghost story, he ends up with the exact opposite.
Mr. Nuttel was supposed to avoid mental excitement and "anything in the nature of violent physical exercise," but receives both. Although it may be the opposite of what the doctor ordered, his visit at the Sappletons' presented him with adrenaline, a workout, and, most importantly, a healthy dose of perspective. After Mr. Nuttel runs away, the reader is left wondering if perhaps these things were exactly what the character needed.
There is situational irony at play in "The Open Window," as Mr. Nuttel's attempts to be polite ultimately result in self-sabotage: he wants to be gracious in front of both Vera and Mrs. Sappleton, but he ends up sprinting out of the house without an explanation—which is, of course, not particularly polite. From the beginning to the end of the story, Mr. Nuttel's prospects of conversing and connecting with Vera and Mrs. Sappleton are stifled by his attempts at observing the meaningless rules of etiquette.
When he is alone with Vera, Mr. Nuttel is silenced by his own desire to give her the most appropriate responses possible. This leaves her in charge of the conversation, which is the opposite of what one would expect of the dynamic between a teenager and an adult. After Mrs. Sappleton appears, he “[makes] a desperate but only partially successful effort to turn the talk on to a less ghastly topic”—namely, his health. He wants so badly not to be seen as rude that he ends up behaving like someone who is either too impolite or too deranged to operate within the social code of the Edwardian leisure class.
‘The doctors agree in ordering me complete rest, an absence of mental excitement, and avoidance of anything in the nature of violent physical exercise,’ announced Framton, who labored under the tolerably wide-spread delusion that total strangers and chance acquaintances are hungry for the least detail of one’s ailments and infirmities, their cause and cure.
Saki uses the indirect interior monologue that follows the portion of dialogue to poke fun at his neurotic protagonist and thereby steer the reader’s sympathies against Mr. Nuttel. The exposition of the story sets the reader up to expect Mr. Nuttel to connect with Mrs. Sappleton, but he undercuts this expectation by never succeeding in expressing himself or behaving as he would like before running out of the house and out of the frame of the story. In this way, Saki uses situational irony to highlight the meaninglessness and impracticality of certain forms of etiquette, as it is Mr. Nuttel's anxieties surrounding correct behavior that reveal him as easy prey to Vera and leave Mrs. Sappleton describing him as "an extraordinary man" who "could only talk about his illnesses."
"The Open Window" features several instances in which the story's comic edge comes from the reader knowing more than some of the characters do. Initially, Vera tricks not only Mr. Nuttel but also the reader with her story about the three men who did not survive their fateful hunting trip three years ago. Eventually, however, the reader realizes that Vera has successfully tricked Mr. Nuttel. At whatever point the reader catches onto this, the rest of the story is extra funny because the reader, having been duped, now shifts from Mr. Nuttel's vantage point to Vera's.
Mr. Nuttel, who is after all present for all of the story's early events, is not the only character that falls prey to dramatic irony. The reader's understanding of the situation definitely exceeds that of Mrs. Sappleton; given that she is absent when Vera tells the story, she is completely in the dark about the key context Mr. Nuttel has about her when she appears in the room. This is why she is astonished when Mr. Nuttel darts off for no apparent reason, before they have a proper conversation and before he gets the chance to meet her husband and brothers.
"'A most extraordinary man, a Mr. Nuttel,' said Mrs. Sappleton, 'could only talk about his illnesses, and dashed off without a word of good-bye or apology when you arrived. One would think he had seen a ghost.'"
The last remark is ironic because only Vera and the reader know that Mr. Nuttel actually did think he had seen a ghost—or rather three. Saki had already had fun with this morbidity earlier in the story: upon seeing the men return from their hunting trip, Mrs. Sappleton essentially tells Mr. Nuttel and Vera that it looks as though the men had been buried alive.
'Here they are at last!' she cried. 'Just in time for tea, and don't they look as if they were muddy up to the eyes!'
Little does Mrs. Sappleton know that this corroborates Vera's claim that the men were engulfed by the bog. It is this exact incongruity between the knowledge of the characters and the knowledge of the reader that makes Mr. Nuttel's reaction to the return of the men and Mrs. Sappleton's reaction to Mr. Nuttel so funny.
Before the story ends, Saki cannot help but play with the characters' and reader's incompatible understandings of the situation. When Vera rationalizes Mr. Nuttel's flight as being prompted by his deep-seated fear of dogs, which she again narrates a story to explain, the audience's relative awareness of what is going on (compared to that of Mrs. Sappleton and the men) further increases. While the reader did not immediately detect the deceptive quality to the story she told Mr. Nuttel about Mrs. Sappleton, it is now obvious to the reader that Vera is a cunning liar who has managed to dupe both a stranger and her aunt. Not only did she shape Mr. Nuttel's knowledge of Mrs. Sappleton, she also shapes the Sappletons' knowledge of Mr. Nuttel. The punch of the story is largely shaped by this dramatic irony, as the reader has slowly gone from gullible receiver of Vera's tall tales to someone on the inside.