Concrete Faery: Book I of the Troutespond Series - Elizabeth Priest - Bog

When it comes to fantasy, the world is always bigger than you think it is… Even when you live in the smallest town in the deepest corner of the country where, by official records, nothing has happened since Vikings stopped pillaging nearby.
Ally Guardian is convinced that the universe wanting anything to do with her is a cosmic joke. Until a strange man appears outside her window and tells her, "I can't speak to you yet." Things only get weirder when she is then implicated in a demonic attack on her history teacher and given the new girl, Alana Larbie, to look after as punishment.
Alana seems to know an awful lot about demons, claiming they got her kicked out of her old school. Together with Ally's oldest friend Tanya, and their one "normal" friend, Teb, they decide to investigate.
The Troutesponde Series is a YA fantasy, working on the premise that if the supernatural did exist, inquisitive teenagers would be the first to notice, and absolutely the worst people ever to interact with it.