Good, fun reading about cholera breaking out in mid-nineteenth century London and the way two men figured out what was really going on. The central character is John Snow, who fights against prevailing superstition and wrong-headed ideas about the nature of disease. The story of Snow’s research is really fascinating, but Johnson loses me a little in his somewhat unfocused ramblings toward the end. The “epilogue” in particular goes on for quite some time about nuclear disarmament. I mean, I get it, but really? I came here for the cholera story, not Johnson’s thoughts on 9/11. Overall, though, this was a great read.