Grimblerod has led twins Asher and Ariana Caine back to ancient Rhyme, a time when Calla and Elora were the same age the twins are now. Though the Kingdom of Falmoor is rich with magic, the twins are unable to use their powers. They don't know whom to trust, where to turn, or how to avoid doing something in the past that may alter the future forever.

Meanwhile, young Teagan Rogers must decide if she is ready to leave behind everything and everyone she knows to follow her mysterious destiny beneath the waves.

Will Teagan choose to become a mermaid?

Will Asher and Ariana get home before changing the course of history forever?

And can enemies truly become friends?