Members of a literary organization known as the Detection Club cowrote the mystery novels The Floating Admiral and Ask a Policeman in 1932 and 1933, respectively. These novels are of interest primarily for what they suggest about literary genre: the microcosms of their composition supply concrete, if playful, models of phenomena also at work in the macrocosm of genre fiction. Thus, collaborative writing emerges as a form of genre laboratory, ideally suited to the small-scale imitation and exploration of superordinate generic processes. Both the writers’ reflections on their collaborative efforts as well as the finished results of said efforts throw into stark relief the interdependent processes of writing and reading, semiotic encoding and interpreting, as they characterize the formation and reformation of generic conventions. Moreover, the ludic facets of the Detection Club collaborations indicate that the notion of (nonliterary) genre-as-game, as embraced by rhetorical genre studies, can be productively applied to literary genre.