What could be a thesis statement for the short story "The Open Window" by Saki?

One thesis statement for an essay on the story could argue that "The Open Window" typifies Saki's style in that he is clever and unconventional, socially satiric, and surprising.

In his social satire, Saki sometimes uses a young character who plays a practical joke upon a priggish and finicky character such as Framton Nuttel. This young personage, such as Vera, is perceptive enough to identify the adult's weakness and exploit it. Often the reader is caught unaware, as well as the character who is satirized.

Vera, the young niece of Mrs. Sappleton to whom Nuttel is to be introduced, exemplifies Saki's subtle satire since her name suggests truth (veracity). When she learns that Mr. Nuttel has come to her area for a rest where he is not acquainted with anyone, Vera takes advantage of his vulnerability and weaves her tale with just enough veracity to convince Nuttel that it is true. She deceives him by supposedly explaining the reason for the open window:

Poor aunt always thinks that they will come back someday. . . . That is why the window is kept open every evening till it is quite dusk."

When the somewhat fatuous Mrs. Sappleton finally enters the scene and tells Framton Nuttel that her men will soon return from hunting by means of the open window, Nuttel is convinced that she is as Vera has described her. As the men arrive, the girl's practical joke upon Nuttel resolves supremely successfully as does Saki's satire.