The unnamed narrator from his cell wants to set the record straight and tells us the story of how he got here.
From the day he is born, he is mild and kind. He loves animals and has lots of them. Taking care of his pets and hanging out with them is his favorite thing to do. His favorite animal companion is his dog.
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.
One night, he 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.
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.