One of the decisive steps in developing narrative cinema took place through the realisation of a dramatic crime on screen. Edwin S. Porter's commercial success with The Great Train Robbery (1903) rests on his understanding of a variety of different genres whilst bending and extending their conventions in order to produce something new and exciting. Moreover, this was a narrative experience which was very much in keeping with the headlines of the day. His film is often thought of as the beginning of the Western genre, but it is the crime that provides the narrative impetus. This chapter will look at films and television programmes which foreground crime and detection relying on mystery and adventure archetypes, but it acknowledges that during the twentieth century crime features in practically all commercial genres. Therefore, the choice of films and television programmes focuses on transitions in the representation of crime and detection on screen as a means to understand the determinants of these changes.