In its golden age, film noir kept to the shadows, shrouding its nefarious schemes in cloaks of cigarette smoke and doom. As was his wont, Orson Welles had the last word. His salty masterpiece Touch of Evil (1958) is cited by purists as the final stop in a stylistic cycle characterized by moral ambiguity and unbridled fatalism. Genres and formal trends come and go, but the singular...