Story: "The Telltale Heart" by Edgar Allan Poe.

In many of Poe's short stories, such as "The Tell-Tale Heart," the narrators are madmen and murderers who fail to disguise their lack of rationality with a discussion of their thought processes. However, their stories inevitably reveal gaps in their chains of thought that speak to their descent into immorality and selfishness. In many cases, insanity is interlocked with the narrators' emotional egotism; they are incapable of empathizing with others and think only of their own desire to satisfy their honor or their need to end the disruptions to their lives.