Mermaid princess Seraphina is framed by her adopted sister Melody for attempting to kill their grandmother. Her family sends her to a cruel penitence hall for three years, where she loses her tail and is forced to wear a mechanical one. After her release, they force her to marry the feared exiled King Alaric of the North Sea. But Alaric is secretly powerful. At their wedding, he protects Seraphina and grants her the North Sea’s power. When Melody strikes again, Alaric saves her.
