In 1518, the city of Strasbourg witnessed an event that still defies explanation.

A woman known as Frau Troffea began dancing in the street—and continued for days. Within a week, dozens had joined her. Within a month, that number may have reached into the hundreds.

There was no music. No clear cause. And no way to stop it.

Contemporary records describe people dancing to the point of exhaustion, injury, and in some cases, death. Authorities, believing the condition was caused by “overheated blood,” encouraged the dancing—only intensifying the outbreak.

Historians and scientists have proposed explanations ranging from ergot poisoning to mass psychogenic illness. But none fully account for the scale, duration, and physical toll of what occurred.

In this episode of Monstrous, we examine the historical accounts, the leadi ...