The Ambivalent Detective in Victorian Sensation Novels studies how the detective as a literary character evolved through the mid-nineteenth century in England, as seen in sensation novels. In contrast to most assumptions about the English detective, Yoon argues that the detective was more often tolerated than admired following the establishment of professional detectives in the London Metropolitan Police Force in 1842. Through studying the historical and literary contexts between the 1840’s to the 1860’s, Yoon argues that the detective was seen as a suspicious, even mistrusted and disdained, figure who was nonetheless viewed as necessary to combat rising levels of crime. The detective as a literary character responded to the often contradictory values and aspirations of the middle class, representing an independent masculinity and laying claim to scientific authority. The detective as a literary construct also policed boundaries around English national identity, often construed against European or colonial others. This study surveys novels by Charles Dickens, Mary Elizabeth Braddon, and Wilkie Collins, alongside lesser-knovwn writers like William Russell, James Redding Ware (pseudonym Andrew Forrester), and William Stephens Hayward. This book contributes to the study of mid-nineteenth-century Victorian culture and connects with broader studies of the detective fiction genre.