In the late nineteenth century, the Egyptian reading public embraced a new entertainment: crime fiction. Translated tales of Sherlock Holmes and Arsène Lupin, in addition to original Arabic stories, were serialized and circulated in literary journals, becoming hugely popular throughout the Ottoman Empire. My project examines for the first time the emergence of this genre in Egypt, positing its rise to popularity in the period 1880-1918 as the confluence of two major, connected epistemological and cultural shifts: the transformation of the category "literature" in Arabic with the expansion of a global literary market, and the universalization of new legal concepts of morality, justice, and truth. Both Egypt's criminal justice system and its burgeoning literary scene were at this point in a state of flux. New courts and policing systems theoretically reproduced European practices of governance, while an influx of European literatures introduced unfamiliar fictional genres – but older forms and practices remained, and the categories "literature" and "law" in Arabic remained unstable. Scholars of literature, intellectual history, and the anthropology of law have examined these two processes separately; my project posits that they are connected, taking detective fiction as a case study through which to examine the convergence of legal and literary discourses in this period. I also highlight the multilingual environment in which these discourses operate, placing Arabic detective fiction in the context long history of interactions between literary and legal texts in Arabic, Ottoman Turkish, French and English. My project investigates the role this fiction played in representing and mediating legal "modernization" for a literate public, and proposes that Arabic literary production more generally was in turn shaped by changes to criminal justice: from Ottoman censorship legislation to circulating notions of secular morality and scientific truth.