Ben Aaronovitch & Andrew Cartmel 
Rivers of London: Detective Stories #3 
Detective Stories #3

The Special Assessment Unit: a small and rather unique department of London’s Metropolitan Police. Small in that it has only two active members, and unique because the crimes it investigates are somewhat unusual in nature. Some might say paranormal. Others might call them supernatural. Either way, they usually involve magic.The SAU’s newest (and second) member, PC Peter Grant, is not just a trainee wizard, but also an ambitious member of the Met, and he’s currently being interviewed as part of the rigorous screening he must undergo to become a police detective.