"Someone is targeting the city's magic practitioners, the members of the supernatural underclass who don't possess enough power to become full-fledged wizards. Many have vanished. Others appear to be victims of suicide. But the murderer has left a calling card at one of the crime scenes - a message for Harry, referencing the book of Exodus and the killing of witches." "Harry sets out to find the killer before he can strike again, but his investigation...