Romancing the Future: Herve Jubert, Devil's Tango (London: Hodder, 2005), translated by Andrea Bell, original copyright date, 2003.
A sequel to Dance With Assassins which I unfortunately haven't read, Devil's Tango is that very rare thing in English, the scientific romance, which isn't a surprise as it wasn't written in English but in French. It's set perhaps a century after the Great Flood, in the apparently Ruritanian Swiss city of Basle--some of the characters have French names, some have German names.
Basle is crime free because particles in the air monitor the behaviour of all citizens, until suddenly a series of murders begin which cannot be traced, and which are being used to destabilise the city. Basle, as one of the last enclaves in a flooded world, is home to gypsies--engineers who have build Historic Districts for the entertainment of the citizens and the preservation of some of the great wonders of the world (such as historic London). In this moment of crisis it is all too easy to blame the stranger, and one of the Mayoral candidates (Fould) is whipping up hatred for his own purposes.
Devil's Tango is a scientific fantasy. The particles which monitor citizens have been developed by the sorcerers of the city in return for civil liberties. The murders are committed by an entity comprised of these same particles, which unite to search for the "genetic markers" which affect the magical DNA of the descendants of as yet unpunished criminals. Yet even this farrago gains a scientific paradigm: it is the shuffling of files from one database to another that has led the Baron of the Mists to confuse the descendant with the ancestor. This is murder through bureaucracy. The villains, Froud and his accomplice Banshee, are engaged in alchemical experiment to bring the devil's child into the world using DNA from a cigarette on which the devil sucked, and elements stolen from the murdered corpses and stored by a golem until they can be downloaded. When the gypsies and the heroes--Roberta Morgenstern and her lover--escape, it is on a ship constructed of the Hidden Cities, a Ruritanian mechanical wonder.
The novel is a mish-mash of science and pseudo-science (herbalism is very popular), of different centuries and many cultures. The result is a world that works because of its inconsistencies, its sense of muddling through. There are no perfect experts here, only people trying to work out the rules of their world.