Friends, Enemies — Rosie Rushton

Tory and her friends Pippa, Ella and Christy have been friends forever -but things are about to change. When Hannah moves to their neighborhood, Tory's mom insists that the girls include her in their group. Tory can't stand the idea of hanging out with whiny, babyish Hannah, and the other girls are equally apprehensive. But this unwelcome guest turns out to be worse than annoying--she's dangerous. Hannah is bent on sabotaging Tory's friendships, and her burgeoning relationship with cute Alex. Now, Tory's will have to convince everyone, including her own mother, that the new girl isn't nearly as innocent as she appears to be.