Theory:

"The Open Window" is an English short story written by Saki. It was first published in the collection "Beasts and Super-Beasts" in \(1914\). The story is so popular that it is often anthologised.
 
The short story deals with a conversation between Mr Nuttel and Vera, where the latter narrates a supposedly tragic story to the former. As a result, Saki's story becomes a frame narrative (or an embedded narrative) as there is a story within the story.
 
"The Open Window" is marked for its witty, concise narrativesurprise ending, and its slightly menacing tone, which are all considered as some of the characteristics of Saki’s works.
 
The major characters of the story are:
  1. Vera, a young girl of fifteen
  2. Mr Framton Nuttel, a nervous visitor
  3. Mrs Sappleton, the hostess
  4. Narrator
  
The minor characters are:
  1. Mr Sappleton
  2. Mrs Sappleton's two brothers
  3. Mr Nuttel's sister
 
Also mentioned is Sappletons' little brown spaniel (the family dog).
 
Moreover, Sappletons' French window that was left open becomes a fictional prop (i.e., a theatrical property) around which Saki lets Vera construct her story.