The three-part miniseries delivers the definitive story of H.H. Holmes, America's first serial killer. H.H. Holmes was the alias of Dr. Herman Webster Mudgett, an evil entrepreneur who took advantage of the millions flocking to Chicago looking for work during the World's Fair in 1893. His pharmacy and World's Fair Hotel provided the perfect facade for the deranged madman to lure victims to his "murder castle". He designed the building himself and built it - in stages and in secrecy - so only he knew the deceptions, from an elaborate maze of death traps to rigging rooms with poisonous gas. He built the castle with stolen money and kept business brisk with dead bodies, selling his victims as skeletons for medical schools. Holmes racked up quite the body count, some believe as many as 200, while also accumulating substantial debt, and his bleak, financial prospects would eventually be his undoing.