After a time, the narrator develops an absolute dread of the cat. When he discovers that the white splash on its breast, which at first was rather indefinite, had "assumed a rigorous distinctness of outline" and was clearly and obviously a hideous, ghastly, and loathsome image of the gallows, he cries out, "Oh, mournful and terrible engine of Horror and of Crime — of Agony and of Death!" As we were able to do in "The Tell-Tale Heart," here we can assume that the change occurs within the mind of the mad man in the same way that he considers this beast to be a reincarnation of the original Pluto.
One day, as he and his wife were going into the cellar, the cat nearly tripped him; he grabbed an axe to kill it, but his wife arrested the blow. He withdrew his arm and then buried the axe in her brain. This sudden gruesome act is not prepared for in any way. It has been repeatedly pointed out that the narrator loved his wife very deeply. Consequently, this act of perversity far exceeds the hanging of Pluto and can only be accounted for by Poe's theme of the perversity of the narrator's acts.
Like the narrator in "The Tell-Tale Heart," the narrator here realizes that he must get rid of the body. He thought of "cutting the corpse into minute fragments," he says, as did the previous narrator in "The Tell-Tale Heart," but rather than dismemberment, he decided to "wall it up in the cellar" in a similar way that Montresor walled up his victim in "The Cask of Amontillado."
The walls next to the projecting chimney lent themselves to this type of interment, and after having accomplished the deed and cleaning up in such a way that nothing was detectable, the narrator decided to put the cat to death. Unaccountably, it had disappeared. After three days, the narrator decided that the "monster of a cat" had disappeared forever; he was now able to sleep soundly in spite of the foul deed that he had done. This lack of guilt is certainly a change from what his feelings were at the beginning of the story.
