The Strange Case of Dr. Jekyll and Mr. Hyde, written by Robert Louis Stevenson, is a classic alternative history mystery novella. The story explores the duality of human nature through the character of Dr. Jekyll, who creates a potion that transforms him into the sinister Mr. Hyde. As the mystery unfolds, readers are taken on a thrilling journey into the dark recesses of the human psyche. Stevenson's masterful storytelling and exploration of moral ambiguity make The Strange Case of Dr. Jekyll and Mr. Hyde a timeless classic in the genre of alternative history mysteries.