The Tell-Tale Heart Edgar Allan Poe

Just one line from the short story says it all: "Presently I heard a slight groan, and I knew it was a groan of mortal terror .. the low stifled sound that arises from the bottom of the soul." A man confronts himself and an unknown listener with his desire to murder an old man. Is it his father? Is the man mad? Is he in jail or an institution? A psychological thriller with many more questions than answers.