Storm Front by Jim Butcher
Harry Dresden is the only professional wizard listed in the Chicago phonebook. He is a private detective, struggling to make ends meet while keeping his city safe from monsters most people believe only exist in fairy tales. Much of his trade deals in locating lost items or people, so it is business as usual when he is hired by a woman to find her missing husband. However, things quickly get complicated when a friend at the Chicago Police Department warns Harry that he himself is the chief suspect in a grisly double murder.