Describe what happens from the time Frampton Nuttel enters the Sappleton home with particular attention to why things happen the way they do in "The Open Window"?

In "The Open Window," Framton Nuttel brings his frayed nerves and letters of introduction to Mrs. Stappleton's home, but flees in terror the same day.
Having arrived at the Stappleton home, Framton Nuttel finds himself sitting across from Mrs. Stappleton's niece, endeavoring to say something that is proper and appropriate.
Secretly, he wonders if this visit and any others will provide him the purported nerve cure he is supposed to be seeking in the countryside.
Holding his letter of introduction, Framton wonders if Mrs. Stappleton is nice.
After a considerable silence, the niece asks, "Do you know many of the people round here?"
Framton explains that he is stranger, but his sister stayed at the rectory for four years and has provided him with letters of introduction.
Then the girl asks, "Then you know practically nothing about my aunt?" and Framton answers, "Only her name and address."
So, Vera dives right in on her tall tale: "Her great tragedy happened just three years ago...that would be since your sister's time." (The niece, Vera, begins, secure in her surety that Framton will suspect nothing since he know no one.)
She begins her tale of how Mr. Stappleton and Mrs. Stappleton's two brothers went out the open window for a "day's shooting." But, tragically, they were "engulfed in a treacherous piece of bog" and never seen again.
Because their bodies were never recovered, Vera adds, "Poor aunt always thinks that they will come back, and walk in the window as they always did." This is why the window is open now.
Vera continues and tells how Mrs. Stappleton's brother Ronnie would return as he sings, "Bertie, why do you bound?" She adds that even she has an eerie feeling as though they might really return.
Framton is completely taken in and unnerved by this tale. So when Mrs. Stappleton enters, he is relieved, thinking all this talk of hunting will end.
When she is seated, Mrs. Stappleton says, "I hope you don't mind the open window...my husband and brothers will be home directly from shooting." She explains that when they return, she always has them enter through the window rather than traipsing over the carpets.
Framton is horrified as Mrs. Stappleton rambles on about the scarcity of birds and the prospects of ducks. He tries to divert Mrs. Stappleton away from such talk, but she keeps looking out the window.
He grows nervous, wishing he had not visited on this tragic anniversary. He tells Mrs. Stappleton that his doctors have prescribed rest and absence of mental excitement, and then he elaborates upon his ailments to which he gets no audience.
Mrs. Stappleton manages a few sounds, but watches intently out the window for her family. Framton looks in sympathy at the niece, but she is staring in feigned open-mouthed horror out the window.
The figures of the men and the dog become visible  in the twilight. As they near the house, one of the boys sings, "I said, Bertie, why do you bound?" This is just as Vera has described him.
Hearing this song that a dead person is supposed to have sung sends Framton racing to grab his things in the hallway as he flees the Stappleton home. He hurries out and down the lane, believing he has seen the dead.
As he approaches, Mr. Stappleton greets his wife outside the window, "Here we are, my dear." He asks who that was he saw that "bolted out" as they arrived. Mrs. Stappleton tells him, "A most extraordinary man." She says he talked incessantly about his ailments, and without even saying good-bye. "One would think he had seen a ghost." She knows nothing of her niece's fabricated tale, and wonders what is wrong.
Nonchalantly, the girl who has caused all this confusion, says, "I expect it was the spaniel....he told me he had a horror of dogs." Then she launches into a tall tale about a pack of dogs that supposedly attacked Nuttel, and he had to spend the night in a newly dug grave. "Romance at short notice was her specialty."