In her hometown of Salem Lily Proctor endures not only life-threatening allergies but humiliation at her first high school party with her best friend and longtime crush, Tristan. But in a different Salem -- one overrun with horrifying creatures and ruled by powerful women called Crucibles, she is Lillian, the strongest and cruelest Crucible ... Lily's other self in an alternate universe that Lily suddenly finds herself where she is torn between responsibilities...

Back in her own universe and ready to start a new life with Rowan by her side, Lily finds she has more difficulties ahead than just keeping her magic hidden since Lillian, ruthless ruler of the Thirteen Cities, is determined that Lily will come back to the alternate Salem, no matter what it takes.