 Although the novel is often referred to as " a mystery " , it is not an example of whodunit or detective fiction . Instead , the central puzzles are the origins of suffering and the motivations of unusual behavior . Characters appear in fragments , with brief scenes providing small clues about their identity . Vautrin , for example , slips in and out of the story – offering advice to Rastignac , ridiculing Goriot , bribing the housekeeper Christophe to let him in after hours – before he is revealed as a master criminal . This pattern of people moving in and out of view mirrors Balzac 's use of characters throughout La Comédie humaine . 
