Not long after Jack the Ripper haunted the ill-lit streets of 1888 London, H.H. Holmes (born Herman Webster Mudgett) dispatched somewhere between 27 and 200 people, mostly single young women, in the churning new metropolis of Chicago; many of the murders occurred during (and exploited) the city's finest moment, the World's Fair of 1893. Larson's breathtaking new history is a novelistic yet wholly factual account of the fair and the mass murderer who lurked within it. Bestselling author Larson (Isaac's Storm) strikes a fine balance between the planning and execution of the vast fair and Holmes's relentless, ghastly activities. The passages about Holmes are compelling and aptly claustrophobic; readers will be glad for the frequent escapes to the relative sanity of Holmes's co-star,...