It's October, and with Samhain approaching, Ember must enter the Cruharach to face the darkest night of her life. As she gives herself over to the Autumn Stalkers and the Leannan Sidhe, she is plunged deep into the shadows of Annwn to face Cernunnos and the test of the Hallowed Hunt.
Meanwhile, the Wild Hunt is trying to contain collateral damage throughout the city. A Fae hate group is terrorizing Seattle, going after shifters and humans alike. In the middle of investigating the deadly cult, Herne takes on a new case.
A frantic wolf-shifter mother begs them for help. Her three-year old daughter has been kidnapped. With three other young girls already dead at the hands of a serial killer dubbed the Angel of Mercy, Herne and Ember find themselves in a desperate race to find the girl before the Angel of Mercy claims another victim.