19th century, Victorian London. As the city’s population explodes, the infrastructure can’t keep up—streets and rivers overflow with filth, and people live packed tightly together in unsanitary conditions.

Then, cholera strikes the city.

At the time, the accepted belief was that disease spread through foul odors (miasma). But one doctor dared to challenge that common sense and sought the true cause of the epidemic through his own revolutionary methods.

His name was John Snow.