Element Girls

Susie, Elizabeth, Tess, and Amelia have been together for as long as they can remember. But things are changing this year, and their friendships are being tested like never before. When Amelia suddenly vanishes, the friends find themselves jetting to Hawaii. They also discover that the amulets they wear as a symbol of their friendship give them elemental powers.
Will their new powers be enough to save Amelia from dangers they didn't even know existed outside of books?