Robert Louis Stevenson's Strange Case of Dr. Jekyll and Mr. Hyde. Jekyll & Hyde

Strange Case of Dr Jekyll and Mr Hyde is the original title of a novella written by the Scottish author Robert Louis Stevenson that was first published in 1886. It is about a London lawyer named Gabriel John Utterson who investigates strange occurrences between his old friend, Dr Henry Jekyll, and the evil Edward Hyde. In this case, there are two personalities within Dr Jekyll, one apparently good and the other evil; completely opposite levels of morality. 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.
Robert Louis Balfour Stevenson (13 November 1850 – 3 December 1894) was a Scottish novelist, poet, essayist, and travel writer. His most famous works are Treasure Island, Kidnapped, and Strange Case of Dr Jekyll and Mr Hyde. A literary celebrity during his lifetime, Stevenson now ranks among the 26 most translated authors in the world.
-Wikipedia.com