It's 1780 in Paris, and the heavy spring rains are saturating the earth.
In a home near the center of town, a basement wall collapses under the pressure, releasing a flood of decomposing corpses, remains from the neighboring Cemetery of the Innocents.
Rumors spread that everyone in the house got sick due to bad air emanating from the decaying flesh.
With the overcrowded cemetery housing generations of dead Parisians, there was a growing worry that the entire city was in grave danger of falling ill.
For centuries, Parisians had buried their dead in the Innocents, the city's largest cemetery.
While cemeteries across Europe were originally placed outside of urban areas, in the ninth century, the church began allowing burials directly on its grounds.
As these urban parish cemeteries filled, some churches started creating bone chapels, like the Sedlec Ossuary in the Czech Republic, to make room for new burials.
By the 18th century, public opinion on urban cemeteries shifted as Enlightenment thinkers and physicians promoted new scientific ideas that linked hygiene to health.
They didn't yet understand the concept of germs, believing instead that disease spread through miasma, or bad air.
Consequently, overcrowded cemeteries spewing cadaverous odors were cast as public health threats.
