This is a fun steampunk-cum-paranormal-cum-Holmesian adventure. It has violence (both physical and magical), powerful wizards fighting for and against Britain (which is ruled by a powerful spirit named Brittania, currently incarnated as the young Queen Victoria), dragons (mostly sleeping), conspiracies and invasions from other countries (such as Germany) trying to take over Britain, and strange non-human humanoids called Shields whose function is to protect wizards (both physically and magically).
The book won’t win prizes for originality. The Holmesian character is a super-genius who operates by science and the science of deduction and uses a suspiciously-named chemical stimulant when he needs a boost. He’s one of a class of people whose name is suspiciously-like that of the mentats in Frank Herbert’s Dune books. The main character is a beautiful, powerful female wizard who works as an agent for the British government but draws her power from dark magic (Death); her Shield is a man-like humanoid who is quick and deadly with a hint of scaly skin; he’s a kind of being called a “Nagah”. Two dragons are involved: the lesser one is a metal dragon who is the ruler and power source behind the steampunk industry section of London. The greater one is asleep deep beneath the British Isles and so gigantic that if it should wake up, all of the British Isles would be destroyed.
It all comes together with a satisfying end.
Recommended if you like this sort of thing.