Because being magically bound to his hot best friend's equally hot stepsister wasn't complicated enough a pack of werewolf bikers has rolled into town.
Caleb needs work. Caleb needs to learn how to manage his new magic. Caleb needs to discover his heritage. Fortunately, thanks to Jadeite, he's now on the right path to addressing at least one of those. Unfortunately Caleb hasn't learned to keep his nose out of other people's business and when he steps in to keep his new employer's son out of trouble that trouble turns on him, taking the form of a werewolf biker chick whose inner wolf has decided Caleb would make a perfect mate. And if that means attacking Caleb and Lexus to prove she's the better fit for him so be it.
Caleb would probably be flattered if there wasn't an entire pack of werewolves ready to tear him to pieces for this unwanted honor.