Crime fiction is a literary genre in which criminal activity or its detection is the central point of the plot. For authors who write genre stories in which a puzzle must be solved, in almost all cases involving a crime, see Category:American mystery writers. Most authors of hardboiled detective fiction, in which both action and puzzle-solving are central, are named as both "crime fiction" and "mystery" writers. Most authors of whodunits, in which the puzzle-solving aspect predominates, are named exclusively as writers in the more specific subcategory of "mystery." Authors of crime fiction in which investigation and solution are nongermane (e.g., The Godfather, The Postman Always Rings Twice) are named in the "crime fiction" category, but not as "mystery" writers.