Steven Johnson is one of today's most exciting writers about popular culture, urban living and new technology. In The Ghost Map he tells the story of the terrifying cholera epidemic that engulfed London in 1854, and the two unlikely heroes - anaesthetist Doctor John Snow and affable clergyman Reverend Henry Whitehead - who defeated the disease through a combination of local knowledge, scientific research and map-making.In telling their extraordinary story, Steven Johnson also explores a whole world of ideas and connections, from urban terror to microbes, ecosystems to the Great Stink, cultural phenomena to street life. Re-creating a London full of dirt, dust heaps, slaughterhouses and scavengers, The Ghost Map is about how huge populations live together, how cities can kill - and how they can save us.