“The Tell-tale Heart” is a story of madness and guilt. Throughout the story, the unnamed narrator continually tries to convince us that he is not mad. He clearly thinks that he comes across as crazy. After all, he has a perfectly logical reason for killing the old man. Evil Eyes simply cannot be tolerated!
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. (enotes etext pdf p. 4)
The narrator descends more and more into madness as he plans and carries out the murder. He fancies himself clever, so he keeps telling himself he will get away with it. The reader begins to suspect that he is just trying to convince himself.
The narrator’s biggest mistake was bringing the police into the old man’s room and chatting with them.
The officers were satisfied. My manner had convinced them. I was singularly at ease. They sat, and while I answered cheerily, they chatted of familiar things. (p. 6)
The police are clearly suspicious, but the narrator is not aware of this. He thinks they are just talking and will not leave. His insistence to prove he is not made has been his downfall. He tried to be too clever, and too cool.
“Villains!” I shrieked, “dissemble no more! I admit the deed!—tear up the planks! here, here!—It is the beating of his hideous heart!” (p. 6)
So he cleverly hid the body, but end up confessing because he hallucinated. Although he was mentally unstable to begin with, the stress of the police being there above the body was too much for him. The heart represents the narrator’s guilt. When he cut up the Old Man and stuck him under the floorboards, he had control of his guilt—but it gradually got to be too much for him, and he ended up hearing the heart and confessing.
Poe made an interesting choice by ending the story here, at its most suspenseful point. Yet there is no need to continue. The story is not really about what happens to the narrator. It is about his guilt. His guilt overwhelms him, and there is no reason to continue the story.