After the narrator has cut out the eye of his cat, Pluto, he feels some remorse and horror at his behavior, and the cat wisely avoids him as they coexist. However, once the narrator announces, "and then came, as if to my final and irrevocable overthrow, the spirit of PERVERSENESS," readers understand that the narrator will inflict further violence upon the cat—which of course he does, once the suspense has built.
When the narrator encounters a second black cat as he is out drinking one night and the cat befriends him, readers understand that this will be a fateful meeting and that in some way the narrator will be made to pay for what he has done to Pluto. The suspense builds as the narrator confesses that he quickly grows to loathe the cat, which is, ironically, missing an eye. The cat's affection builds the narrator's fear and loathing as it climbs over him and he chronically finds it underfoot.
As the police repeatedly search the narrator's cellar, the suspense builds: will they discover the body of his murdered wife where he has placed her inside the wall? The last bit of suspense in the story is the question of what is making the sound from her tomb; it is, of course, the cat, which gives the murderer away to the police.