Wilkie Collins's The Moonstone is widely regarded as a landmark in the history of British detective fiction. As a prototypical detective novel, it also exhibits influences from many fictional genres. In this essay, I focus on the coming-ofage plot in the novel and analyze how The Moonstone rewrites the Bildungsroman for its self-fashioning as detective fiction. Through a modern individual's successful socialization, the classical Bildungsroman expresses the belief that organic national culture can domesticate social mobility in the age of rapid modernization and imperial expansion. Collins's novel reproduces this coming-of-age narrative and demonstrates the restoration of social normalcy in the face of colonial threats posed to the imperial center. This essay contends, however, that the coming-of-age narrative and the detective narrative bifurcate as Blake, the central character who comes of age at the end, fails to develop necessary agency for detective work. During a time of increasing class conflicts allied to exploitative transnational economy, the normative socio-national fabric the Bildungsroman symbolizes proves to be incompetent. Instead, the agency that restores national identity and completes Blake's coming of age derives from subjects associated with social uprootedness and degeneration, those who compromise the cultural logic of the Bildungsroman. The coming-of-age narrative in this quasi-detective novel provides a normative fa<;:ade but fails to solve the problem for which it is summoned. This essay discusses how a detective fiction emerges in dialectic with the Bildungsroman.