Melanie Avalon and Scott Emmens take you inside the twisted mind and bone-chilling exploits of America’s first known serial killer: H. H. Holmes. Beneath the polished facade of a charming doctor and businessman, Holmes constructed his infamous “Murder Castle” during the 1893 Chicago World’s Fair—a labyrinthine hotel rigged with trapdoors, gas chambers, and secret chutes designed for death. What drove this calculating killer? How did he lure his victims? And what secrets were sealed behind the walls of his macabre mansion? From his early cons to the haunting discovery of his body count, they uncover the shocking psychology, staggering manipulation, and sheer horror behind one of the most disturbing chapters in American true crime.