What is the mood of a story?

If the question is regarding how to find or discover the mood in the story, there are some steps that can be taken to effectively determine this.  One way to "read" this is to examine the level of narration and how the story unfolds.  Oftentimes, the author will be deliberate in attempting to convey a mood to the reader through word choice, descriptive language, and also the manner in which the story is explained.  For example, the narration schematic of Holden Caulfield, in Catcher in the Rye helps to illuminate how he sees the world and the mood of his narration.   At the same time, the mood of a story can be conveyed through setting elements.  For example, Shakespeare's MacBeth uses a great deal of the theory of correspondence, where natural weather conditions helps to bring a great deal of light on the thematic elements of the story.  Sometimes, the mood can be expressed through characters themselves, especially in their physical description.  In Rushdie's Midnight's Children, Saleem Sinai is described in extreme detail, especially his nose and the powers of smell (and nasal drainage) he possesses.  This helps to illuminate the idea of Saleem's magical powers as a child of midnight and also helps to bring out the mood of the pain in Partition, where the Indian subcontinent was divided as eyes (Bangladesh and Pakistan), nose (India), and nasal release (Sri Lanka).  Sometimes, authors will convey the mood of the story in these types of manners.  If trying to determine the mood, pay special attention to the "hints" the author gives.