An analysis of a short story should contain descriptions of the story's plot, theme, setting, characterization, and style. Here are summaries of these various elements that you can expand upon.
In the short story "The Cask of Amontillado" by Edgar Allen Poe, the narrator, a man named Montresor, meets another man named Fortunato at a carnival. Fortunato is dressed in a jester's costume and is already quite drunk. Montresor informs Fortunato that he has obtained a quantity of Amontillado, a type of sherry, and subtly persuades him to accompany him to his wine vaults to sample it. Once they are deep within the catacombs, Montresor locks Fortunato in chains and constructs a wall to bury him there alive.
The theme of the story is obviously revenge. Poe alludes to this in the first sentence: "The thousand injuries of Fortunato I had borne as I best could, but when he ventured upon insult I vowed revenge."
The setting of the story adds to the horrific atmosphere that leads up to the murder of Fortunato. It begins at dusk during "the supreme madness of the carnival season." The madness of the initial backdrop foreshadows the madness of the murder to follow. From the wild atmosphere of the carnival, Poe takes his readers into the frightening darkness of the vaults under Montresor's palazzo. These tunnels contain the bones of Montresor's ancestors, and niter lines the walls like spider webs. This setting is truly terrifying.
There are two main characters. Montresor, the murderer, narrates the story. He seems to be insane. He expresses no regret at all for the heinous crime he is committing and describes it as if it were fully justified and normal. He says that he has received injuries and insults from Fortunato, but he never elaborates on these, and the reader is left to wonder if he has imagined them. Fortunato, the victim, is presented in a jester's costume. He is vain about his ability to judge fine wines, and he is drunk, but otherwise there is no indication that he is guilty of anything worthy of death. This is a further indication that he does not deserve the fate he comes to at the end of the story and that Montresor is insane.
Poe's style of writing in the story is a blend of ornate description and sparse dialog. The patches of dialog break up the descriptions and make "The Cask of Amontillado" easier to read and follow than other Poe stories that rely on long paragraphs of intricate description. The effect of this blend of description and dialog is to propel readers relentlessly towards the story's horrifying conclusion.