Since you are writing a letter, be sure to begin with a salutation, such as “Dear Mr. Poe.” Follow that up with the body of your letter. The prompt gives you the option to explore parts of the story that you found “interesting or disturbing.” You are free to explore your own thoughts on that. The following is an example of how you might begin the letter:
Dear Mr. Poe,
I just finished reading your short story "The Cask of Amontillado." You have outdone yourself once again. I have been a long time fan of your stories, because I find them particularly interesting and disturbing. One reason I found this story interesting is that we never find out why Montresor kills Fortunato. I mean, he does admit that Fortunato repeatedly injured him, but it was the insult that put Montresor on the path to revenge. My interest was high throughout the story because I wanted to know exactly what Fortunato had done or said to or about Montresor. I was disappointed that I never found out, but I think your goal was to let the reader’s mind imagine a scenario or insult.
At that point, you might discuss the parts that you found mundane or unnecessary. My suggestion to you would be to compliment Poe on not having many—if any—parts that qualify as mundane or unnecessary. It is a short story, so Poe is working hard to give readers only the details that they absolutely need. For example, reading about Montresor dismissing his servants might feel like extraneous knowledge, but it is critical information to have because it shows the depth of his planning. He waits for a convenient time to have the house to himself.
Continue your letter by discussing the story’s setting and how it impacts the atmosphere. This portion of your letter should have the most specific textual references. Feel free to explore the setting of the carnival itself; however, I recommend that you focus on Montresor’s house. I would specifically explore the catacombs themselves. Montresor made sure that his house was empty, so the murder could have happened anywhere within the confines of that space, but Poe set the story and murder within the catacombs. This particular setting helps add to the story’s creepy and foreboding atmosphere. We know that Montresor is planning on something, but we don’t know what. His plans are sinister, and the location heightens those feelings. The men descend into dark, damp, and narrow corridors, and those spaces are full of bones in the walls and the floor. The following quote is a good description of the presence of death in the catacombs:
At the most remote end of the crypt there appeared another less spacious. Its walls had been lined with human remains, piled to the vault overhead, in the fashion of the great catacombs of Paris. Three sides of this interior crypt were still ornamented in this manner. From the fourth the bones had been thrown down, and lay promiscuously upon the earth, forming at one point a mound of some size.
The catacombs are a place of death, and so that setting further hints at Montresor’s sinister plans. As the men descend, our feelings of worry increase. A sense of foreboding grows. For those reasons, you could claim in your letter that words like "dark," "scary," "sinister," "morbid," or "eerie" are strong adjectives to describe Poe’s writing style.
Be sure to finish your letter by again thanking Poe for his story, and close the letter with "sincerely" or another sign-off, followed by your signature.