Most historical turning points are loud, a war or a revolution. The one in this episode was silent. While Victorian London looked up at the sky for an invisible killer, one quiet anesthetist looked down at the dirt. This is a deep dive into Dr. John Snow, the 19th-century English physician who founded modern epidemiology by mapping the deaths of his neighbors.

We trace his path from a working-class Yorkshire upbringing to the front lines of Britain's pioneering work in anesthesia (he personally administered chloroform to Queen Victoria during the births of two of her children). Then we follow him into the 1854 Broad Street outbreak in Soho, where he rejected the dominant miasma theory ("blaming bad air for cholera was like blaming a bad smell for a house fire") and teamed up with Reverend Henry Whitehead to interview survivors and pl ...