White Night: The Dresden Files, Book 9

Meet Harry Dresden, Chicago's first (and only) Wizard P.I. Turns out the 'everyday' world is full of strange and magical things - and most of them don't play well with humans. That's where Harry comes in.A series of apparent suicides rings alarm bells with the police, and Harry is hired. At the first crime scene he hits pay dirt, discovering an unmistakable magical taint. There's also a message especially for him, and it ain't pretty. The 'killings' will continue if Harry can't halt his tormentor, but the evidence implicates his half-brother, which just doesn't add up. Unfortunately Harry's digging around attracts some powerful vampires with a stake in the result. Soon, whichever way he turns, Harry will find himself outnumbered, outclassed and dangerously susceptible to temptation. And if he screws up, his friends will die.Magic - it can get a guy killed.