Unleashed - Nancy Holder

When Katelyn starts at her new school. the only person she knows is the handsome and intriguing Trick Sokolov, an acquaintance of her grandfather. She's surprised when the popular Cordelia Fenner invites her home and when she meets Cordelia's hot cousin, she begins to think her new life might be OK after all.

But as she spends time with the family, she realises that the Fenners are harbouring a deep dark secret. Every bone in Katelyn's body tells her that the Fenners are mad, bad and dangerous to know - but how can she give up her only friend, and how can she ignore the way Justin sets her blood on fire with a single look?

Katelyn finds herself caught between three major werewolf clans who have been at war with each other for centuries - a war, it seems, that Katelyn is destined to end.