How does Vera get away with it in The Open Window?

Vera is a teller of tales, a young woman whose forte is "romance at short notice." She is an exquisite and intuitive actress, equally skilled at deceit and its concealment. While Nuttel waits with her for Mrs. Sappleton to appear, Vera relates an elaborate story surrounding a window in the room that has been left open. It is this story, of the death of some relatives who went hunting long ago, that eventually causes Framton Nuttel's breakdown. She tells Nuttel that the window is left open as a sign of her aunt's hope that the dead hunters will one day come home and provides a detailed description of the men, their behavior and attire. After Nuttel flees upon seeing these men return, just as Vera has described them, Vera invents a story explaining his departure as well. Saki refers to Vera as "self-possessed," which literally means that she has self-control and poise. In the context of this story, it is clear that this is the quality that allows her to he so well-Vera's self-possession allows her to maintain a cool head and calm believability while relating the most outlandish of tales.