Rivers of London by Ben Aaronovitch
Peter Grant was just a probationary constable in the Metropolitan Police Service when one night, in pursuance of a murder inquiry, he tried to take a witness statement from someone who was dead but disturbingly voluble, thus bringing him to the attention of Inspector Nightingale, the last wizard in England.
Now Peter is a Detective Constable and a trainee wizard, the first apprentice in fifty years and his world has become somewhat more complicated: nests of vampires in Purley, negotiating a truce between the warring god and goddess of the Thames, digging up graves in Covent Garden.
There’s something festering at the heart of London, a malicious vengeful spirit that takes ordinary Londoners and twists them into grotesque mannequins to act out its drama of violence and despair. The spirit of riot and rebellion has awakened in the city and it falls to Peter to bring order out of chaos – or die trying.