Book excerpt: Tracing hitherto unexplored aspects of the evolution of official detective agencies between the late eighteenth and the twentieth century, this is the first book to discuss detective agencies in a variety of national contexts, including England, France, the U.S.A, New Zealand, and Germany. The comparative studies included in this collection provide new insights into the development of both plainclothes policing and law enforcement in general, illuminating the historical importance of bureaucratic and administrative changes that occurred within the state system.