Edgar Allan Poe, "The Cask of Amontillado" (1846) from Edgar Allan Poe: Poetry & Tales:
Oh, just a month too early for Halloween, we have one of my favorite creepy Poe stories. Actually, all Poe stories are my favorite, whether they depict obsession ("The Oblong Box"), cleverness ("The Gold-Bug"), feverish mistakes ("The Sphinx"), comedic misapprehension ("The Spectacles"), metaphysical fantasy ("The Island of the Fay"), or something else entirely ("The Philosophy of Furniture"). Here we have a story that seems pretty simple: a revenge fantasy about a guy who wants to come up with the perfect crime. (Not to be confused with "The Imp of the Perverse," "The Black Cat," "The Tell-Tale Heart," or his many other revenge-filled stories.)
The LoA page gives some possible background: it's about Poe feuding with his ex-friend Thomas Dunn English. That may be true, but Poe would make an excellent victim in an Agatha Christie novel precisely because his feuds were so large, numerous, and sometimes (to him) inexplicable. I wouldn't want to pathologize him as manic-depressive; much better to simply say that he was one weird dude, capable of publishing an essay deeply cutting some writer and then sending out a letter to that writer looking for a piece to publish in his magazine. (Some of this was due to the anonymous nature of some of these publications: Poe might publish a critique and then claim not to be the critiquer. But everyone knew how cutting he could be: one of his nicknames was "The Tomahawk Man." More likely he had that sort common sociopathy where he often thought people were being unfair to him when they critiqued him, but thought he was simply "telling it like it is.")
So I wouldn't jump to say that this piece is about his feud with T. D. English, though it's about getting revenge on someone, getting away with it, and making sure they know it was you who did it. Also, if we think about this as an attack on English, we might miss the usual Poe trope of doubling killer and victim. (Most clear use of that trope: "William Wilson.") Here, the to-be-killed Fortunato is a real whiz when it comes to wines--just like his to-be-killer, Montressor. There's also all the doubling where Montressor repeats Fortunato's lines, as in the famous "For the love of God."
We also see why Poe is considered one of the well-springs for the detective story, which here is given a noir edge: Montressor tricks Fortunato by making Fortunato think the idea to go to the vaults is his; while Montressor also shows how he can say one thing (telling his servants to stay) to mean another (making sure his servants will leave). We also see this irony when Montressor eventually agrees with Fortunato that he will not die from his cold.
But for all the buried, ironic, morbid humor of this piece, that ending is still a moment of great horror: Montressor hasn't been telling us this story while Fortunato has been dying, but many years after--when he's long dead.