Trust the Instinct (Teen Wolf, Book Two, Worlds Colliding series)

In the second book of Stacie Stilinski, Arielle "Ari" Martin, Tara Hale, and new girl Natalie Lahey, everyone is getting ready to face each other.

Stacie Stilinski feels like a helpless victim frequently, an obstacle in the way, a little girl who could easily get herself or others hurt. And she hates it that it's her greatest weakness.

Ari Martin is struggling with her status as a werewolf, her relationship with her cousin Lydia, keeping the truth from her when all she wants to do is tell her everything, and the very complicated relationship with her parents.

Tara Hale is no longer trusting of Derek since she found out that he knew who had tried to kill her with the rest of their family six years ago, and he had never spoke a word to her. She's also the only one from the pack that actually wants to help Scott, Ari and their friends, except when it comes to the Kanima. While Derek is turning all of these teens, Tara doesn't like it, because of survival and other means. But after a while, Tara finally starts to care about the pack, and she finally starts to trust her own brother again.

Natalie Lahey was a scared, self-conscious girl afraid of her father, who used to abuse not just Isaac, but her as well. When Lahey tries to search for Isaac, he brings Natalie as a form of leverage. When the Kanima killed Lahey, it had unintentionally tried to kill Natalie. Isaac brings a weak, close to death Natalie to Derek, begging him to turn her to save her life. While he does, it is come to realization that Natalie used to be best friends with Ari, Stacie and Adriana, Ari's missing twin sister. This is a past that none of them can forget, either hate, friendship or forgiveness.

They've all come face to face with their enemies and each other.

And now the only thing left to do is fight.