The Haunting Of Alaizabel Cray

Victorian London overrun by the wych-kin, demonic creatures that have rendered the city uninhabitable south of the river, and which stalk the streets after dark. When Thaniel Fox, a young wych-hunter, finds a mad girl wandering the streets in the middle of the night, he is moved by pity to take her home; and in doing so, he becomes embroiled in a plot that reaches into the highest levels of government, and into the darkest depths of the wych-kin's world.