In 1878, more than 5,000 people died in Memphis of yellow fever outnumbering the combined death tolls of the Great Chicago Fire, the San Francisco earthquake, and the Johnstown flood. A huge disaster, to be sure, but one that presents challenges for Molly Caldwell Crosby in her attempts to construct a compelling emotional story in The American Plague. The chief problem: Whenever she introduces a character, he or she dies (that's the nature of writing about epidemics, I suppose). Thankfully, only about a third of her history of yellow fever is set in Memphis; the most gripping parts take place in Cuba after 1898's Spanish-American War. A group of doctors was sent there to help eradicate the disease, and they eventually discovered that it's spread by mosquitoes, not through the air or dirty linens. (Not surprisingly, one died outright from yellow fever.) Plague is a sometimes fascinating look at a very narrow period of American medical history.