The narrator insists he is sane, but tells the story of murdering an old man because of his disturbing “vulture-like” eye. He watches the man for several nights, carefully planning the crime.
After killing him, he hides the body under the floorboards and initially feels calm, believing he has committed the perfect crime. Soon, however, he begins to hear a growing heartbeat coming from beneath the floor.
The sound becomes louder and more unbearable, filling him with guilt and panic. He becomes convinced that the police can hear it too.