Pack Challenge opens with Sara getting drunk off her ass in celebration of her grandmother's death. The fact that the abusive woman died months ago and the whole town is still ecstatic, shows just how evil the old bat was. During Sara's revelry, she ends up sticking her tongue down a biker's throat, but before things go much further Sara is pried off the guy by her two best friends. Sara isn't really someone who gropes random men without the motivation of tequila, so when the biker shows up at her work the next day she's a bit embarrassed.
Sara was an interesting character. Her leg is screwed up from when she was mauled by a mountain lion, so she spends 90 percent of the book limping around town. Turns out that the lion was actually a shifter seeking revenge against Sara's family and, with the death of her grandmother, the lion is back to trying to kill her. Bad thing is that Sara doesn't know that monsters are real and she especially doesn't know that she's a wolf shifter.
I really don't care for storylines centered on the main character discovering that vampires, werewolves, etc. are real. The whole chain of denial, proving, and slowly coming to terms gets a little boring. That was my main problem with this book. I got bored with Sara slowly discovering the paranormal aspects of her world, especially since it eclipsed the whole lions are trying to kill her plot.
The romance between Sara and the hero (Zach) was also dull. I liked Zach, but he wasn't the most interesting Laurenston hero I've read. Zach has a game plan and that doesn't include a meaningful relationship. His current goal is to become pack leader and sleep with a crap ton of women. So when he meets Sara he's immediately intrigued and scared shit-less by the intense attraction he has to her. He's determined to just tell her she's a wolf shifter and high-tail it out of town. But, of course, things don't go according to his plan.
All in all, I'd recommend this book for fans of Shelly Laurenston, but if you're looking to get into this author I would suggest starting with Beast Behaving Badly.