Broken Homes by Ben Aaronovitch

Amina has never been comfortable in the spotlight. She is happy just hanging out with her best friend, Soojin. Except now that she’s in middle school everything feel. A mutilated body in Crawley. Another killer on the loose. The prime suspect is one Robert Weil; an associate of the twisted magician known as the Faceless Man? Or just a common or garden serial killer?

Before PC Peter Grant can get his head round the case a town planner going under a tube train and a stolen grimoire are adding to his case-load. So far so London.

But then Peter gets word of something very odd happening in Elephant and Castle, on a housing estate designed by a nutter, built by charlatans and inhabited by the truly desperate.Is there a connection? And if there is, why oh why did it have to be South of the River?