City of Secrets - Adventures of Letty Parker, #1

Letty Parker lives by her wits. Estranged from her family, she sells pies on the streets of Bristol. But this is a Bristol full of dark secrets, peopled by gangs, monsters, dragons and gargoyles - and by creatures older than time. When her friend and stepsister disappear, when members of Jeb's gang vanish, Letty is plunged headlong into a conspiracy where homeless children are being spirited away to a place where a terrible fate awaits them.
These are the poor and the lost children of the streets whom no one seems to care about - except for Letty. But what if a rich child went missing? Would the authorities then act? Together, Letty and Jeb hatch a plan.