The Spirit Realm — Emily Page

After incidents involving a guinea pig, a plastic chair, and the principal's office, Amira and Alicia fall into a different world called the Spirit Realm, a place filled with souls that have been kidnapped from their former bodies after death. There they meet a small army which is trying to save the souls, and Eden, a handsome, easygoing boy. The girls learn that they have the power to control and create nearly everything in the known universe, and that they could be the saviors of the Spirit Realm, with the help of new, mysterious powers. But the enemy wants Amira and Alicia on its side, too. What if one girl is destined to join the enemy? And what if she has to break her sister's heart to do it?