From his prison cell, the unnamed narrator is writing the story of how everything in his life fell apart. Since he will die the next day, he wants to set the record straight, and tells us the story of his life…
From the day he is born, he is mild and kind. He loves animals and has lots of them. As he gets older up these qualities grow stronger. Taking care of his pets and hanging out with them is his favorite thing to do. His favorite animal companion is his dog.
Before long, he gets married. His wife loves animals too, and fills the house with a variety of them. One of these is a humongous, all black, super-smart cat named Pluto. When the man starts drinking, his personality takes a turn for the worse. He starts physically and verbally abusing his wife and pets. One night, the narrator comes home from partying completely drunk. Thinking Pluto didn't want to hang out with him, he grabs the cat and cuts his eye out with a pen-knife.
One morning, not long after the eye-gouging, the narrator is overcome with a perverse impulse. He hangs Pluto from a tree in his garden, murdering him. Writing from his jail cell, the narrator claims he did it precisely because he knew it was wrong. That night, the night of the murder, the man's house catches fire and burns down. Only the man, his wife, and one servant are left alive. But, they lose all their money in the flames, along with the house. When the narrator returns the next day, there is a crowd in his bedroom, looking at his bedroom wall. On the wall is the slightly raised image of a "gigantic cat" with a rope around its neck (11).
Since he left the cat hanging all day and all night, he figures one of the neighbors cut it down and then threw it through his window to wake him up. Somehow it stuck in the plaster of the wall. This bothers the man for a long time.
One night when he's out drinking, another black cat appears on the scene. This cat looks just like Pluto, except for the little white spot on his chest. The man takes the cat home, and his wife is quite pleased.
When it is discovered that this cat is also missing an eye, the man begins to despise it, while the woman loves it all the more. After some time passes, the woman shows the man that the white spot on the cat's fur has grown. Oddly, the white spot now forms an image of "the GALLOWS!" (21). (The gallows is a wooden device used to hang people.)
The man is too afraid of the cat to abuse it. The cat never leaves him alone for a moment, and even sits on his chest and breathes in his face when he is in bed. So, the man doesn't get any sleep. As his loathing of the cat increases, so does his physical and verbal abuse of his wife. One day he and his wife go down to the cellar of the crummy old house they live in now that they are poor. The cat follows them. In a fit of extreme irritation, the man tries to kill the cat with an axe. The woman stops him, and the man "burie[s] the axe in her brain," killing her (23).
The narrator wonders how best to conceal the body? After much deliberation, the man decides to hide the body in a space behind the cellar wall. That night, the man sleeps peacefully for the first time in ages. The cat is nowhere to be seen.
The cops come around, but the man has finesses them. No big deal. On the fourth day, still no cat. But, the police return and search the house again, especially the cellar. Right when they are about to leave, abandoning their search of the cellar, the narrator decides to start bragging about how well built the house is. He takes his cane and hits it against the spot in the wall where he's hidden his wife's body.
A noise answers his knock! It is a sad sound, like a kid crying. It sounds horrible and desperate, but also victorious. The police are on it. They take down the wall only to find the dead body, with the cat on top of its head. And that's why the narrator is in jail, sentenced to death by hanging. The narrator had accidentally shut the cat up in the wall with the body.