Freda Swift 
Music of the Fairground [EPUB ebook] 

When Jessica Hale is a young girl visiting her grand parents. She finds a hidden door to a fairground. Here she is given a power while does not emerge until she is an adult. Earth is under an attack by a creature from another planet residing in another dimension. With two friends and three special artifacts she will journey into the other dimension to find and destroy the alien and her army. They make new friends and face new perils on their journey.