Adam Stemple & Jane Yolen 
Stone Cold [PDF ebook] 
Book 1

When young runaway Craig prepares to jump from a church rooftop, his salvation comes in the unholy shape of Silex: a beast trapped in the form of a gargoyle. Silex runs an investigative service, chasing redemption from atop his perch. And he needs a young lad to do his footwork. Craig begins his new life by probing a series of murders that has menaced Scotland. The scenes are frightening, the motivation is a mystery, and the authorities are no help. So along with Father Harris, a hard-edged man of the cloth, Craig steps onto the streets of Edinburgh and toward the dangerous task of catching a killer.