In The Tell-Tale Heart, an unreliable narrator describes his hatred of the 'evil eye' belonging to the old man he is living with. The narrator plots the old man's murder with all the machinations of a sadistic madman; yet, he insists that he has not lost his grip on his own sanity.

For seven nights, he finds himself unsuccessful in carrying out the intended murder. He asserts that the old man's 'evil eye' was closed, rendering his mission impossible to complete. After all, he reasons that it was this eye which was his true antagonist, not the old man himself. At this point, we are led to question the narrator's lucidity. On the eighth night, he actually waits a whole hour in the old man's room after the old man cries out.

When he hears the old man groaning, the narrator is ecstatic; he thinks that he has finally succeeded in terrifying the old man. He fancies that he recognizes the old man's 'groan of mortal terror' as mirroring those of his own from nights past. What he says he knows well is the sound of fear.

He leads us to believe that he sympathizes with the old man and pities him for being afraid. However, his claim does not seem credible because of his obvious delight ( 'chuckled at heart') in reducing the old man to a pitiful figure of cowering fear. The narrator's words betray his sadistic and cruel nature. Not only is he without remorse for the crime he is about to commit, he is obscenely happy with himself for what he considers his clever planning of the old man's murder.