This article offers a deeper understanding of Hugo’s social philosophy as expressed in Les Misérables through a reading of the novel’s treatment of prostitution and Parisian sewers in the context of contemporary thought. Specifically, Hugo reframes the prostitute-as-sewer metaphor that was commonplace among contemporaries such as Parent-Duchâtelet. First, in the story of Fantine, he provides a narrative articulation of the social problem of prostitution that reveals the full import of Parent-Duchâtelet’s work on the subject. Then he offers an alternate understanding of the sewer to which the prostitute was often compared, and simultaneously expands his metaphorical treatment of the sewers to include all of society’s outcasts. Hugo thus rewrites prevailing social thought to advocate for a new relationship between society and its most disadvantaged members as well as the reintegration of les misérables into the social whole.