Unravel Me (Shatter Me #2) by Tahereh Mafi (2013, Paperback)

It should have taken Juliette a single touch to kill Warner. But his mysterious immunity to her deadly power has left her shaken, wondering why her ultimate defense mechanism failed against the person she most needs protection from.

She and Adam were able to escape Warner’s clutches and join up with a group of rebels, many of whom have powers of their own. Juliette will finally be able to actively fight against The Reestablishment and try to fix her broken world. And perhaps these new allies can help her shed light on the secret behind Adam’s—and Warner’s—immunity to her killer skin.