The antagonist is an unreliable narrator. He begins by telling us that he is not mad but diseased, and the disease is sharpening his senses, which makes him hear things, "In the heaven, in the Earth, and in hell." He continues to tell the reader how calmly he can tell the story of how he killed an old man because his "evil" eye.
The narrator continues to be kind to the old man by asking how he slept every night. He only asks that to see if the old man suspects that he is stalking him through the night. Every night, the narrator opens the old mans door just enough to fit his head through, it normally took him an hour to fit his head. He did this just to explain how cautious he is. However, he can not kill him because the eye is closed.
May I search the building?!
On the eighth night of watching the old man sleep, he gets a little to self confident and chuckles at himself, but little does he know that the old man is awake and sitting straight up in his bed. They have a one hour standoff and during this entire hour, the narrator starts hearing a low, dull, quick sound. The noise reminded him of a watch enveloped in cotton, however, we know that the sound symbolizes the narrator's increasing anxiety. The narrator open the lantern and noticed the eye was open. The narrator was scared that the neighbors would hear something.
On the eight night, the suspense reaches its highest point and the narrator kills the old man. The narrator murders the old man by pulling him off the bed and smothering him with the mattress. Before the murder, however, the narrator gives us some clues in the form of foreshadowing and personification when he says, "Death, in approaching him, had stalked before him with his black shadow."
After he knew the old man was dead he cut him up into pieces and washed the blood away. After the blood was washed away he put the remains of the body under the floor boards. The next thing he knew the police were at the front door. The narrator suspects the neighbors heard the noise. He invites the police inside to search the place. The narrator sits on top of the body, and starts the heart the sound again. He starts to think its the old mans heart, but really its just his heart because he in nervous.
The narrator starts to suspect that the police are making fun of him and calling him insane. The heart beat gets louder, the narrator couldn't take it anymore. So he confessed to the murder, because he couldn't stand the heart beat.