The antagonist is the unreliable narrator who thinks that he is not mad. The Narrator wants to prove that he is sane. He argues that he is nervous and his disease sharpened his senses. However, the Narrator can tell the story very calmly of how he killed the old man in the old man's house. The Narrator means no harm and loves the old man, but his "evil eye" pushes him to commit the muder.
The Narrator continuously proves that he is sane by explaining how wise he is. The first step of his plan is to be kind to the old man for a whole week. For seven nights the narrator looks at the old man sleeping at midnight to see if the evil eye was open. The narrator opens the lantern and for seven nights, he doesn't see the eye open. So, the narrator cannot kill the old man. The narrator questions how the old man slept to see if he suspects anything. The personification in the story when the narrator death stalks the old man.
I am so wise and nobody will ever know that I killed him.
The narrator slips his finger off the lantern and makes a sound so loud that the old man wakes up. For one hour the old man sits up in bed to see if anybody is outside his window, but really the danger is in the room with him. The narrator opens the lantern and sees the evil eye open. The narrator hears a low, dull, quick sound and believes it to be the old man's heart. The sound is getting louder and makes him feel more nervous than ever. The narrator chuckles at the fear of the old man, but his laugh will be heard by a neighbor. The laugh from the narrator being heard from a neighbor foreshadows that the police are going to be called.
I confess. I killed the old man.
On the eighth night the suspense builds when the narrator kills the old man because of his vulture eye. The narrator pulls the old man under his mattress and suffocates him till death.
The narrator proves he's wise by dismembering the body in the bathtub. He then hides the dismembered corpse under the floor boards. The police arrive at the house because the neighbor heard a shriek coming from the old man's house. The police searches the house and the police come up empty, but the narrator invites the police to sit. The narrator places his chair right above where he place the old man's body. The narrator starts to hear the old man's heart. The sound of the old man's heart symbolizes the narrator's guilt. The narrator starts freaking out because the sound is getting louder and louder.
The narrator can't take the sound anymore and confesses. The sound of the heartbeat is actually the narrator's guilt which means there is an internal conflict.