On the eve of Siren Phillips' twelfth birthday, she learns that she is destined to turn into a Mermaid. Siren must struggle with her new reality, saying goodbye to her mother and friends, while she transitions into the water while being chased by a group of Hunters. When Siren's mother is taken, the town must rally behind her, and help her make a peaceful transition into the water, before the hunters can find out where she is.