Scholar of Decay — Tanya Huff

When Aurek Nuiken travels to Richemulot to search for a spellbook that will save his endangered wife, little does he know that a beautiful woman, a family of wererats, and his own brother will cruelly conspire to turn the tables against him. As hideous monsters of Ravenloft close in, he is drawn to the brink of madness in a world that preys on the innocent.