The Changeling

Some of us are born to be magic. Aoife is an ordinary teenager, hanging out with her childhood friend Carla, putting up with school. The worst she has to contend with is that the boy of Carla's dreams is trying to get off with her instead. But then, after chasing a lost little girl no one seems to be able to see, Aoife starts to develop mysterious powers. Eventually her parents confess that she isn't their real daughter.
Their human child was stolen by the fairies, and Aoife is the changeling left behind in her place. Shocked and disorientated, Aoife turns to Shay, the taciturn farmer's son who is the only person who might believe her story. Together, they embark on a dangerous journey, which takes them deep into the underworld and changes everything they thought they knew about fairies.