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

The Strange Case of Dr Jekyll and Mr Hyde is a gothic novella. 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.
​The novella’s impact is such that it has become a part of the language, with the very phrase “Jekyll and Hyde” entering the vernacular to refer to people with an unpredictably dual nature: usually very good, but sometimes shockingly evil.