What is the irony used in "The Open Window"? Explain this irony with quotes from the story.

"The Open Window" is a humorous short story, and part of the humor stems from the irony at work within it. In the story, a man named Framton Nuttel is introducing himself around the neighborhood as a means of "helping the nerve cure which he was supposed to be undergoing."
In one instance, he is talking to the fifteen-year-old niece of a woman named Mrs. Sappleton while he awaits the arrival of the aunt. Normally a fifteen-year-old would be portrayed as someone impulsive and naive. However, the niece is described as "self-possessed" and speaks to Mr. Nutter in an inquisitive, almost sly way. She asks him if he knows many people in the neighborhood, clarifying that he "knows practically nothing" about her aunt. She then launches into a story about her missing uncle and other relatives, who probably drowned years ago in a bog, and her aunt's delusional behavior of keeping a window open, believing that they shall return each day. Their disappearance is a lie, but Nuttel believes the girl and is shocked when the men return, running off "without a word of goodbye or apology," believing he has seen ghosts.The rest of her family, having no idea what caused Nutter to run off, is then treated to a story, spun by the niece, regarding a phobia that Nuttel had of dogs, due to having been "once hunted into a cemetery somewhere on the banks of the Ganges by a pack of pariah dogs," at which time he "had to spend the night in a newly dug grave with the creatures snarling and grinning and foaming just above him."This is a major aspect of the humor and irony of the story, as this young woman, who is essentially a child, is so intelligent and insightful that she is able to quickly ascertain Nuttel's character and come up with a story to manipulate him for her own entertainment.