A gripping tale of one of history's most bizarre events, and what it reveals about the strange possibilities of human nature

In the searing July heat of 1518, Frau Troffea stepped into the streets of Strasbourg and began to dance. Bathed in sweat, she continued to dance. Overcome with exhaustion, she stopped, and then resumed her solitary jig a few hours later. Over the next two months, roughly four hundred people succumbed to the same agonizing compulsion. At its peak, the epidemic claimed the lives of fifteen men, women, and children a day. Possibly 100 people danced to...