Robert Stevenson 
The Strange Case of Dr. Jekyll and Mr. Hyde [EPUB ebook] 

Can good and evil exist in one body? A London lawyer John Utterson investigates strange occurrences between his old friend Dr. Henry Jekyll and the evil Edward Hyde. The novella’s impact is such that it has become a part of the language, with the very phrase Jekyll and Hyde coming to mean a person who is vastly different in moral character from one situation to the next or associated with a medical condition called split personality. The story may also serve as interpretation of a concept in Victorian culture, that of the inner conflict of humanity’s sense of good and evil.