📝 Between 1918 and 1919, a killer stalked New Orleans and cut down Italian grocers in their beds. Who was he, and did the jazz he demanded truly spare anyone? When police failed, the killer mailed a letter promising to spare any home where jazz was playing. On the night of March 19, 1919, the city threw a desperate dance party. The killer never struck again.

On the night of March 31, 1922, six people were slaughtered with a mattock on a remote Bavarian farm called Hinterkaifeck. The killer didn't just strike and flee—he stayed. For three days beforehand, neighbors reported seeing strange footprints in the snow, hearing footsteps in the attic, and finding unfamiliar newspapers inside the house. No one was ever convicted. The case remains Germany's most infamous unsolved mass murder, a haunting document of how evil can arrive slowly, invisibly, and stay for dinner.

In July 1518, a single woman began dancing in the streets of Strasbourg. Within weeks, hundreds had joined her—convulsing, leaping, spinning for days without rest. Some danced until their feet bled. Some danced until their hearts gave out. Physicians declared it a "natural disease" caused by hot blood. The city built a wooden stage and hired musicians, believing more dancing would cure the dancers. It only made things worse. By September, dozens were dead. The Dancing Plague of 1518 remains one of history's most baffling mass psychogenic events—a documented mystery that science still struggles to fully explain.