"The Strange Case of Dr. Jekyll and Mr. Hyde" by Robert Louis Stevenson is a Gothic horror novella published in 1886. When London lawyer Gabriel John Utterson investigates strange occurrences involving his old friend Dr. Henry Jekyll and a murderous criminal named Edward Hyde, he uncovers a disturbing mystery. This defining work of Gothic horror explores the duality of human nature and has profoundly influenced popular culture, making "Jekyll and Hyde" synonymous with hidden evil beneath respectable appearances.