"The Tell-Tale Heart" is told from a first-person narrative of an unnamed narrator, who insists on being sane, but is suffering from a disease (nervousness) which causes "over-acuteness of the senses".

The old man with whom the narrator lives has a clouded, pale, blue "vulture-like" eye, which distresses and manipulates the narrator so much that the narrator plots to murder the old man, despite also insisting that the narrator loves the old man. The narrator is insistent that this careful precision in committing the murder proves that they cannot possibly be insane. For seven nights, the narrator opens the door of the old man's room to shine a sliver of light onto the "evil eye." However, the old man's vulture-eye is always closed, making it impossible to "do the work," thus making the narrator go further into distress.

On the eighth night, the old man awakens after the narrator's hand slips and makes a noise, interrupting the narrator's nightly ritual. The narrator does not draw back and, after some time, decides to open the lantern. A single thin ray of light shines out and lands precisely on the "evil eye," revealing that it is wide open. The narrator hears the old man's heart beating, which only gets louder and louder. This increases the narrator’s anxiety to the point where the narrator decides to strike; jumping out with a loud yell and smothering the old man with his own bed. The narrator then dismembers the body and conceals the pieces under the floorboards and ensures the concealment of all signs of the crime. Even so, the old man's scream during the night causes a neighbor to report to the police, who the narrator invites in to look around. The narrator claims that the scream heard was the narrator's own in a nightmare and that the man is absent in the country. Confident that they will not find any evidence of the murder, the narrator brings chairs for them and they sit in the old man's room. The chairs are placed on the very spot where the body is concealed; the police suspect nothing, and the narrator has a pleasant and easy manner.

The narrator begins to feel uncomfortable and notices a ringing in the narrator's ears. As the ringing grows louder, the narrator concludes that it is the heartbeat of the old man coming from under the floorboards. The sound increases steadily to the narrator, though the officers seem to pay no attention to it. Terrified by the violent beating of the heart and convinced that the officers are aware not only of the heartbeat but also of the narrator's guilt, the narrator breaks down and confesses. The narrator tells them to tear up the floorboards to reveal the remains of the old man's body.

True! --nervous --very, very dreadfully nervous I had been and am; but why will you say that I am mad? The disease had sharpened my senses --not destroyed --not dulled them. Above all was the sense of hearing acute.

It is impossible to say how first the idea entered my brain; but once conceived, it haunted me day and night. Object there was none. Passion there was none. I loved the old man. He had never wronged me. He had never given me insult. For his gold I had no desire. I think it was his eye! yes, it was this! He had the eye of a vulture --a pale blue eye, with a film over it. Whenever it fell upon me, my blood ran cold; and so by degrees --very gradually --I made up my mind to take the life of the old man, and thus rid myself of the eye forever.

The Tell Tale Heart is one of Edgar Allan Poe's finest works. In this short story, Poe uses an unreliable narrator. The narrator is the servant of an old man. The narrator tries to convince us that he is sane by describing the minute details of the murder he committed.