In the exposition, the narrator is trying to explain that he is not crazy. Instead, he says that he is nervous, very nervous. He also explains the reason behind the murder of the old man. It was because of his pale eye.
Climax
In the first rising action, the narrator is seen creeping into the old man's room every night for 7 days at 12:00 PM. While the old man slept, the narrator watched but can't kill him because the old man's eye is closed
Falling Action
In the next rising action, while the old man slept his eye was open. So the narrator was able to kill him, but the old man awoke to a noise. The old man tried going back to sleep calming himself by saying it was just the creaking floor or it was just a mouse walking on the floor
Resolution
In the climax, the narrator abruptly murders the old man by suffocating him with a mattress. And then cuts his limbs off and moments later hides the body.
In the falling action, the old man's neighbor calls the police on them after hearing a scream. The police arrive and the narrator tells them that it was his own scream and gives them a tour of the house.
In the resolution, the narrator comes to what used to be the old man's bed. Then hears the beating of the heart. After a few minutes of this, the man was filled with guilt and couldn't take it anymore. So he confessed himself and showed the police the body.