For countless years, Silex has kept vigil over Edinburgh atop a local church. A demon bound in stone, Silex solves the mysteries of the city below. But now a mystery lurks inside the church, in the form of a young woman seeking sanctuary. Looking panicked and speaking little of her past, the girls raises Silex's suspicions. Craig, Silex's human assistant, has a more welcoming spirit, but he lacks the experience of his gargoyle mentor. When they discover the young women's connection to the new threats menacing Edinburgh, will they be prepared for the danger that comes next?