The inescapability of guilt is arguably the most important theme in “The Tell-Tale Heart.” Try as he might, the unreliable narrator is never able to escape his guilty conscience, as manifested by the insistent sound of the beating heart beneath the floorboards.

This sound torments the narrator, making it impossible for him to avoid the consequences of his wicked actions. It is all too easy to commit such a crime; but it is much more difficult to live with the consequences. And the narrator cannot live with them, hence his confessing what he did to the police.

It could be pointed out, in contradiction to the above, that the narrator attempts to dissociate himself from his crime, claiming that the murder victim, the old man, was somehow responsible for his own death.

That's perfectly true, but blaming the old man can still be seen as a way of dealing with a guilty conscience, even if it means evading responsibility for what's happened. Just because we feel guilty about something, it doesn't necessarily mean that we'll come right out and confess our guilt. It's perfectly possible to deny what we've done while still being tormented by a guilty conscience, and that certainly seems to be the case here.

One of the major themes in “The Tell-Tale Heart” is the effects of guilt or conscience and the descent into madness.  In the story, the narrator’s sanity is definitely in question.  He kills the old man because of his “evil eye” but then feels guilty about it.

The story depicts a rapid devolving of the narrator’s psyche.  At first he is very proud of himself, and considers himself very clever to have gotten away with the murder.  When the police arrive, he coolly tells them there is nothing wrong, then leads them into the old man’s room.

In the enthusiasm of my confidence, I brought chairs into the room, and desired them here to rest from their fatigues, while I myself, in the wild audacity of my perfect triumph, placed my own seat upon the very spot beneath which reposed the corpse of the victim. (p. 6)

However, his confidence gets the better of him.  While he is in that room, his guilty conscience starts to bother him.  He begins to imagine that the old man’s heart is still beating.

But, ere long, I felt myself getting pale and wished them gone. My head ached, and I fancied a ringing in my ears… (p. 6)

The ringing in his ears represents his conscience, and his growing mental instability.

It was a low, dull, quick sound—much such a sound as a watch makes when enveloped in cotton. I gasped for breath—and yet the officers heard it not. I talked more quickly—more vehemently; but the noise steadily increased. (p. 6)

The narrator begins to act more and more erratically, arguing “about trifles, in a high key and with violent gesticulations” (p. 6)

Ultimately, it becomes obvious that the narrator is losing his mind, and it might have been clear to the police all along—why else would they stay and talk about nothing?

“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)

Quotes from: http://www.enotes.com/tell-tale-heart-text

"The Tell-Tale Heart" is what is generally called a perfect-crime story. In this extremely common genre a man or woman commits what he or she considers a perfect crime, usually a murder, but some little clue gives the murderer away. This formula was used in the old radio shows for many years, and then used in television shows. It was used repeatedly in "Alfred Hitchcock Presents" on television and later on the highly successful show "Columbo," starring Peter Falk. The theme of most perfect-crime stories is "There is no such thing as a perfect crime," or it might be stated as "Murder will out." Poe wrote several perfect-crime stories in which the murderer is caught because of something he overlooked, but he also wrote one perfect-crime story in which the murderer actually gets away with it. That was "The Cask of Amontillado." Editors in Poe's day would not accept a murder story in which the murderer was successful, but Poe was able to publish "The Cask of Amontillado" because he set it in a foreign country in the distant past. Anyway, the theme of "The Tell-Tale Heart" is "There is no such thing as a perfect crime."

The thematic subject may be guilt, but the theme is that the human heart cannot endure the burden of guilt, especially in the case of murder. The guilty must confess somehow or be consumed by his/her conscience.

Hint: Whenever you are looking for the theme in a story, ask yourself, what idea about life comes to my mind after reading this story? Or, is there some kind of lesson learned by any of the characters? Usually, the theme can be applied to more than just the story.

What is the overall theme of "The Tell-Tale Heart" by Edgar Allan Poe?

The most prominent theme of Poe's classic short story is the effects of guilt on the human psyche. The unreliable narrator is depicted as a madman who is initially composed and focused as he carefully plans and executes a seemingly perfect crime. The narrator brags about how he cautiously proceeded to dismember the old man's body, drain the victim's blood in the bathtub, and conceal the corpse underneath the floorboards. The narrator believes that his composure during the ordeal is evidence of his sanity and initially experiences no feelings of guilt. When the police arrive at his home, the narrator casually invites them in and carries on a pleasant conversation with them. However, the murderer begins to hear the steady beating of the old man's heart coming from underneath the floorboards. The beating of the old man's heart becomes louder and louder until the narrator can no longer ignore it. The murderer ends up confessing to his crime and shows the police officers where he hid the dismembered body shortly after they arrive. After brutally murdering the old man, the narrator becomes overwhelmed with guilt and believes that he hears the sound of the old man's heart beating underneath the floorboards. The unreliable narrator's auditory hallucinations and insanity are a result of his guilty conscience and tortured soul, emphasizing the effects of guilt on the human psyche.

What is the overall theme of "The Tell-Tale Heart" by Edgar Allan Poe?

In the short story "The Tell-Tale Heart" by Edgar Allan Poe, the theme which is the most obvious is the theme of guilt or innocence. If you remember that theme is the lesson about life that the author is trying to teach the reader, the narrator is both insane and guilty.  The narrator denies the insanity and admits his guilt in the killing of the old man.  Yet underneath the obvious theme is the theme or idea that humans have a terrible time dealing with guilt as shown in the narrator's nervousness especially when the police come to the house.  Only the narrator hears the beating of the old man's heart which leads him to finally confess to the police as he cannot continue to hide his guilt.

What are the themes of the "The Tell-Tale Heart" by Edgar Allan Poe?

This question has been asked and answered. Please refer to the link below and thanks for using eNotes.

http://www.enotes.com/tell-tale-heart/q-and-a/what-all-themes-tell-tale-heart-by-edgar-allan-poe-203309

What is the underlying theme of "The Tell-Tale Heart" and why is this the theme?

Another theme of this text has to do with the narrator's terrible fear of death. It actually causes him to kill an old man that he claims to love, simply because the old man's eye seems to remind him of death. He calls it "the eye of a vulture," and vultures are scavengers who are very much associated with death, because they eat carcasses of dead animals; they only appear when such carcasses are to be found. Likewise, the "pale blue" color of the old man's eye and the "film over it" make it sound like he has cataracts, an ocular disease associated with the elderly. Further, the narrator begins his nightly ritual of attempting to kill the old man at "about midnight" each night for a week, and midnight is also often symbolic of death (which fits here, given the narrator's intention toward the old man). On the final night of the old man's life, the old man wakes up and emits "a groan of mortal terror," and the narrator says he knows the sound well. He continues,

Many a night, just at midnight, when all the world slept, it has welled up from my own bosom, deepening, with its dreadful echo, the terrors that distracted me. I say I knew it well. I knew what the old man felt, and pitied him . . .

The old man fears for his life when he hears the narrator in the dark at his door, and the narrator indirectly admits that he also fears death, that he has uttered the same terrible groan in the middle of the night. It appears, then, that our fear of death can cause us to do strange and terrible things. Furthermore, our fear of death can even drive us crazy.

What is the underlying theme of "The Tell-Tale Heart" and why is this the theme?

There are actually two possible themes for this short story. 

The first underlying theme is the evil that we have within ourselves is often worse than the evil that might be seen from outward appearances.  This is a theme in the story because the old man is clearly ugly and has a revolting eye (which causes the narrator to do what he does in the story.  Other than his physical being looking evil, the old man is seemingly harmless to others.  However, it is the narrator who has the evil within him that allows him to murder the old man for absolutely no reason.

The second theme is that our guilt sometimes gets the best of us.  After the narrator kills the old man, he hears a continuous beating, which he can not identify.  This noise drives him insane to the point that he gives himself up to the police officers without even being questioned.  Therefore, it was the build up of guilt within the narrator that forced him to admit to his crime.

What is the theme of "The Tell-Tale Heart"?

This question has also been previously answered. Please see the link below for more information.

What is the theme of "The Tell-Tale Heart"?

Theme in story-telling is usually one of the main focuses of the story, so whenever you are trying to find out the theme of a story, try summarizing the underlying subject matter in one or two words.  In this story, it can be summed up with "insanity".  We have a narrator who kills a man because the man's eye bugs him, then hears the man's heartbeat after he is dead.  Sounds crazy, right?  Well, the narrator is aware that we think it is crazy, and so tells the story from the viewpoint of one who is trying to defend his sanity.  There can be a big debate about the sanity of the narrator, and so that is why that is a major theme.  Tied into that is the concept of guilt; we know the narrator is guilty, he never denies it.  But, did his guilt drive him to confess, or was it his "insanity"?  So, how did guilt play a role in the story?

I provided a link below to further discussion of some themes in the story, and that should help too.  Good luck!