This thesis explores how penny dreadfuls published between 1839 and 1868 used the urban guide persona to radically reconstruct and politicise hidden institutions in the metropolis. Existing research on penny serials illuminates how these texts articulated issues of class disparity in the city by weaving fictional narratives with snippets of journalism, commissioner’s reports and various other external, authoritative sources. I extend current scholarship by focusing the way penny dreadfuls map the city, and its social ills, by guiding the reader into institutions not widely represented in middle-class literature: factories, brothels, convents and asylums. More specifically, I suggest that numerous penny dreadfuls adopt the rhetoric of the guide or social investigator to critique representations of what Michel Foucault calls ‘other spaces’ in the city, spaces that were subject to philanthropic interest and public outrage throughout the mid-nineteenth century. These concealed, exploitative institutions were often presented in the press as aberrant, entirely separate from the progressive morals of the metropolis. However, rather than completely imitating the press reports into these spaces, the penny dreadfuls explored in this thesis allow the reader voyeuristically to trespass into these prohibited spaces whilst simultaneously questioning the ‘otherness’ of such sites. Drawing on a wide range of hitherto neglected texts, including many discovered from archival research, I show how these serials moved beyond the purely sensational to address the ways that the populations of such spaces were oppressed through asymmetrical power dynamics, socio-economic factors and lack of government or public intervention. In doing so I add to a growing body of work reappraising penny serials and arguing for the significance of their contribution to Victorian literary culture.