London, 1854. A mysterious and deadly illness is sweeping through Soho, and people are dropping like flies. The leading theory? “Bad air.” But one doctor isn’t convinced. John Snow begins to trace the outbreak — not through symptoms, but through streets.  Journalist and author Sandra Hempel tells Marc Fennell (Stuff The British Stole) the story of how a hand-drawn map, a pub, and a pump sparked the birth of epidemiology — and changed the way we fight disease forever.   Binge all the episodes of No One Saw It Coming now on the ABC listen app (Australia) or wherever you get your podcasts. Get in touch: Got a story for us? We'd love to hear from you! Email us at noonesawitcoming@abc.net.au