It's one of the most successful--and surprising--of phenomena in the entire crime fiction genre: detectives (and proto-detectives) solving crimes in earlier eras. Barry Forshaw has written a lively, wide-ranging and immensely informed history of the genre, which might be said to have begun in earnest with Ellis Peters' crime-solving monk Brother Cadfael in the 1970s and Umberto Eco's The Name of the Rose in 1980 (with another monkish detective), but...