I reserved Ben Aaronovitch's Rivers of London after a recommendation from a good friend. While we have different tastes, we're both fans of Harry Potter and so it's not surprising that she read ROL as it is described as if 'Harry grew up and joined the fuzz'. It isn't as literal as that but it is definitely a good line to use for those who have trepidation into delving into the paranormal/fantasy genre. Or for those who have grown up with the Potter books and are now looking for a more adult read without all the sexy time that vampire novels seem to be so concerned with.
Peter Gant has just finished his probationary period with the MET, and is afraid that he's going to be stuck on desk duty, rather than being a 'proper' copper. After a strange meeting while guarding a crime scene, Peter is informed the next day that he is to join the Economic and Specialist Crime Unit. The only other member of the unit is DCI Nightingale, and Peter is required to move to 'The Folly' where he is inducted into the world of the supernatural.
What follows is a good crime story, with plenty of twists so at times I had no idea what to expect next. There's a few parts that are obvious, but I'm willing to overlook them because I love that Aaronovitch can appropriately distribute his vast knowledge of London and it's history throughout the book.