How does Vera set the scene for the perfect reveal?

At the beginning of the short story, Vera asks Mr. Nuttel several questions concerning whether he is familiar with her aunt or the area. After discovering that Framton Nuttel is an absolutely clueless hypochondriac, Vera begins to concoct a false story about her aunt's "tragedy."
Vera takes note of the large French window and is aware that her aunt's husband and two younger brothers left earlier that day to shoot their guns in the country. She proceeds to tell Framton a made-up tale about their tragic deaths, all while knowing that they will return from their trip any minute. Vera convinces Mr. Nuttel that the story is true by acting disturbed and feigning sympathy for her aunt. Vera also remembers to include an exact description of her uncles' attire in her story to set the scene for the perfect reveal. When Vera's uncles arrive, she stares out the open window with "dazed horror in her eyes." Framton then sees the three figures walking towards the window and bolts out of the home without saying goodbye.
Overall, Vera recollects the details of her uncles' appearances, takes note of the open window where they typically enter the home, and is aware that they will return while Mr. Nuttel is visiting. Vera then behaves like a concerned niece and tells Framton the false story regarding her uncles' tragic deaths. When they arrive, Vera acts horrified, which convinces Framton Nuttel that he is actually watching ghosts enter the residence.