The Tell-Tale Heart by Edgar Allan Poe

A nameless narrator, tormented by an old man’s "vulture eye," becomes obsessed with eliminating his perceived tormentor. As he meticulously plans the perfect crime, he believes himself to be the pinnacle of reason and intelligence. Yet, after the deed is done, an overwhelming sense of paranoia begins to unravel his mind. The sound of a heartbeat, growing louder and louder, drives him to madness in a psychological battle he cannot win. This chilling short story is a masterclass in suspense, guilt, and the fragile nature of the human psyche.