The life of a mermaid seems easygoing. Most people would imagine mermaids swimming all day, singing, being pretty. But unfortunately, the life of this mysterious underwater creature isn't so carefree as thought. The underwater life of Hali Waverly hasn't always been so easy. Both parents had vanished recently, fighting in a long, brutal, but now ended war. A younger brother and an enormous amount of money wasn't all her parents left behind to Hali: a throne, and an entire kingdom. With her older siblings gone and unable to take the throne for her, Hali refuses this responsibility. The young heir retreats to land, leaving the throne to her unprepared and careless brother. Oblivious of the ongoing fight undersea, Hali receives an urgent message: A war has been declared on her underwater kingdom by their former enemy, blaming Hali for stealing a priceless crown. With non-stop storms and hurricanes, the young mermaid is forced to leave the comforts of land, on a quest to hunt down the king's vanished diadem and restore peace among her people. Accompanied by friends, along the way, Hali may learn more than just the location of the lost crown.