What is the main conflict in Shattered Mirror by Amelia Atwater-Rhodes?

Sarah Vida is a vampire hunter by night but carries on the semblance of a normal teenager during the day. She attends school and has just been forced to change schools as the story opens. Sarah has gone alone into a den of vampires and been injured, prompting a visit to a healer, Caryn Smoke. Caryn warns Sarah that there are vampires at her new school in Action, Massachusetts, but assures her that they are living a peaceful lifestyle.