The Cracked Mirror

Two sisters named Ally and Elizabeth were having a normal afternoon when they found an unusual mirror in their attic. They accidentally enter the mirror which takes them to another dimension where they have to fight some bad guys. Ally escapes but leaves her sister behind. Ally finds two siblings named Lucy and Greg. They tell her she has to get back to her dimension before the mirror completely cracks. What will Ally do to get her sister and get back to her dimension before the mirror completely breaks?