Broken Homes by Ben Aaronovitch
Formerly a screenwriter, Ben Aaronovitch has since made a new name for himself with his novels about DC Peter Grant, of which this is the fourth.
Peter’s a fairly typical London cop – except for being the Met’s first apprentice wizard in decades. Along with his mentor, DCI Nightingale, and colleague Lesley May, he’s responsible for policing London’s supernatural side.
The climax leaves some plot threads hanging, presumably to be picked up again, but it provides enough of a resolution to satisfy.