'Crime Fiction' by John Scaggs
An excellent read, the best analysis I've come across so far. It's chronological like most guides, but focuses a lot more on the undercurrents and genre conventions - mirroring, the 'othering' of the criminal, Barthesian readerly/writerly texts and even textual panopticons as well as the usual range of conventions (loner, place as character, street language, flawed characters, the conflict between individual and collective). It moves further than most guides in its examination of the sociological and cultural forces that birthed each stage and subgenre of crime fiction.
Particularly interesting was his section on the police procedural, which he argues emerged from the lawlessness of the hard boiled era as a way of restoring confidence in the collective nature of policing. Yet he argues this evolution still allows for the dual nature of the hero in police procedurals. The hero functions as a team player but still remains the wayward individualist of the hard boiled era.
Scraggs, J. (2005). Crime Fiction. London, Routledge.