What message or moral does "The Tell-Tale Heart" give to the readers?
Edgar Allan Poe's "The Tell-Tale Heart" is an early example of a story with the message or moral "Murder will out." There have been thousands of such "perfect-crime" stories written ever since. Typically in such a story the protagonist commits a murder which is planned and executed so perfectly that he does not expect to be caught. But he overlooks one detail which gives him away to the police. In the case of "The Tell-Tale Heart," the narrator is caught because of his own nervousness and guilty conscience.
TRUE!—NERVOUS—VERY, very dreadfully nervous I had been and am;
This is only one of the myriad ways in which a murderer can get caught and punished. His guilt and nervousness cause him to imagine that he can hear the victim's heart beating so loudly that the investigating officers must be hearing it as well. He thinks they are playing cat-and-mouse with him, only pretending not to hear the beating heart. Finally he can stand the strain no longer; he breaks down and confesses.
“Villains!” I shrieked, “dissemble no more! I admit the deed!—tear up the planks! here, here!—It is the beating of his hideous heart!”
Edgar Allan Poe's "The Black Cat" is another perfect-crime story with the same message or moral that "Murder will out." The narrator murders his wife and conceals her body behind a thick wall. But he doesn't realize that he has inadvertently walled in his nemesis, a black cat, which attracts the attention of the investigating officers with its yowling. They break through the wall and discover a horrible scene.
The corpse, already greatly decayed and clotted with gore, stood erect before the eyes of the spectators. Upon its head, with red extended mouth and solitary eye of fire, sat the hideous beast whose craft had seduced me into murder, and whose informing voice had consigned me to the hangman. I had walled the monster up within the tomb!
The murderer had overlooked one minor detail in committing the perfect murder. These perfect-crime stories involving murder generally imply that there will always be something that will give the murderer away.