Crystal White, formerly an ordinary human, is finally back together with her true love: the handsome, charming mer-prince Llyr. Granted supernatural abilities of her own that will allow her to live underwater, Crystal finally seems to have a shot at happiness with the man she’s waited for so long. Not, however, if obstacles both below and above the ocean have anything to say about it. Llyr’s undersea domain is becoming increasingly discontented by their relationship and to make matters worse, ancient denizens of the Black Seas are capitalizing on this to wage a formidable war. Meanwhile, Crystal’s human friends begin to learn of her secret love for the mer-prince, sending shockwaves across the land and sea. With social pressures surrounding her above and all-too-physical threats lurking in the waters below, Crystal finds herself increasingly torn between two worlds. Will she and Llyr together conquer the dangers in their way, or will Crystal once more have to say farewell to the watery depths?