The Firm of Nucingen

The entire story is told as a conversation between four "cormorants" (the metaphor is Balzac's) who sit and drink in a private room while their talk is overheard through the paper-thin partition and reported to us by Balzac himself (or a fictional representative of the writer). The book is told in the style of an oral narrator who never seems to quite get around to the point of the story - and indeed the various digressions are what enable such a wide range of characters to feature.