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

Dr Jekyll, a ‘large, well-made, smooth-faced man of fifty’, occasionally feels he is battling between the good and evil within himself, thus leading to the struggle between his dual personalities of Dr Jekyll and Mr Hyde. He has spent a great part of his life trying to repress evil urges that were not fitting for a man of his stature. He creates a potion in an attempt to mask this hidden evil within his personality. However in doing so Jekyll is transformed into the smaller, younger, cruel, remorseless, evil Edward Hyde. Dr Jekyll has many friends and has a friendly personality, but as Mr Hyde, he becomes mysterious and violent.