The expertise of Saki as a short story writer is certainly apparent in his "The Open Window" as he employs the clever use of the window as the symbolic perimeter of the frame story that Mrs. Sappleton's niece concocts in order to exploit the nervous condition of Framton Nuttel. This use of the window as the setting of the narrative of the niece is particularly effective because an open window suggests with its openness a certain truthfulness and candor.
Thus, by employing the window from which Mr. Sappleton and his son have departed to hunt as the frame within which she fabricates her story, the niece lends realistic detail and veracity--notice her name, Vera--to her tall-tale so much so that she has effected a blurring of the distinction between imagination and reality. Because this condition exists, when the two men do appear and pass through the open window, the nervous Framton is horrified at what he perceives as ghosts. Clearly, the use of the open window is the all-important device for Vera's "romance at short notice."