Nightschool, Volume 3: The Weirn Books — Svetlana Chmakova

Betrayed by one of their own, the Hunters have become the hunted as their hideaway is invaded by a pack of ravenous werewolves! But it'll take more than a few mongrels to get the better of these kids. Meanwhile, Alex begins advanced training with Mr. Roi. Will he be able to help her find a clue to her sister's disappearance? Or is the home-schooled Alex in way over her head?