Quite fittingly for this Tuesday's post, I thought I'd suggest The Rivers of London by Ben Aaronovitch. I plucked this book from my bookshelf (it's handy having a housemate who reads) and liked the sound of a detective story combined with magic set against the city of London.
Following Peter Grant, a newly appointed police officer, as he works on his first big case, is recruited into a special (almost secret) department and works to learn the first of an encyclopedia of magic spells.
It's a good fun book and while I wasn't actually sure about it, decided to pick up the second in the series and am just about to start the third one. I think the aspect I most enjoy about it is how London is portrayed. Aaronovitch describes it in great detail and it's exciting to be able to picture exactly where Grant is running (to or from) and learning some new historical tidbits about the city I love.
I'm not sure if this would be much fun to read if you didn't know London- I'd love to hear from anyone who fits that description!