When fierce mermaids and manipulative sirens invade Rayburn with deadly melodies, Theo and Morana must unite their factions to stop a subaquatic takeover, unaware that a dark evolution awaits Milo and a shifting tide threatens to wash them away forever.
With Theo and Morana gone, the burden of leadership falls upon Pearl and Triton as a feral pack of nameless beasts invades Rayburn to claim the ancient Moonstone, forcing the land and sea factions into a final, brutal stand for survival.
