The Abyss Lord's Mermaid

Mermaid princess Thea cuts off her own tail to travel to land, seeking her captured sister Lillian. She is trapped in a water prison and makes a dangerous blood pact with Nemesis, the sealed Lord of the Abyss. United, they stand against the ruthless human King Sauron. The king tortures sea people to craft lethal mechanical weapons. Thea awakens her full siren power, paying a terrible price.