The Hollow Girl — Hillary Monahan

Five boys attacked her.
Now they must repay her with their blood and flesh.

Bethan is the apprentice to a green healer named Drina in a clan of Welsh Romanies. Her life is happy and ordered and modest, as required by Roma custom, except for one thing: Silas, the son of the chieftain, has been secretly harassing her.

One night, Silas and his friends brutally assault Bethan and a half-Roma friend, Martyn. As empty and hopeless as she feels from the attack, she asks Drina to bring Martyn back from death's door. “There is always a price for this kind of magic,” Drina warns. The way to save him is gruesome. Bethan must collect grisly pieces to fuel the spell: an ear, some hair, an eye, a nose, and fingers.

She gives the boys who assaulted her a chance to come forward and apologize. And when they don't, she knows exactly where to collect her ingredients to save Martyn.