When Madge receives a moonstone necklace on her sixteenth birthday, she discovers she is not only a mermaid, but also, a witch.

Problem is, she never knew either existed in the first place.

As if wrapping her head around the fact that she's a mermaid-witch isn't enough, it also turns out her parents were royalty to her kind and didn't die as she's been told her entire life. Instead, they were murdered by her estranged aunt Viviane, who is now after her.

If Madge is to prove herself fit to lead her kind, she'll have to hone her newfound Vala and unravel clues from her mother's tome. But when Madge uncovers the dark power her murderous aunt wields, will she have what it takes to save them all?