Mrs. Sappleton says that Mr. Nuttel dashed off so fast "one would think he had seen a ghost." Why is this statment an example of dramatic irony?
Dramatic irony is created in a scene when the reader knows and understands more than a character or characters understand. The humorous ending of this story is achieved through dramatic irony. When poor Mr. Nuttel runs out, scared to death, we know why. Vera has "set him up" by making up a story about Mr. Sappleton and Mrs. Sappleton's brother drowning on a hunting trip; she says Mrs. Sappleton still waits for them to return, even leaving the window open for them so that they can walk in when they return. In fact, Mr. Sappleton and the brother are out hunting at that moment. When they do return and step through the open window, Mr. Nuttel believes he really has seen ghosts. Mrs. Sappleton's statement about his having seen a ghost becomes especially funny.
There is one more example of dramatic irony immediately after Mrs. Sappleton's remark. Vera explains Mr. Nuttel's behavior by making up another story, this one about Mr. Nuttel's having spent the night in an open grave. Mrs. Sappleton and the others believe her, of course, but we know better. Vera is quite a storyteller!