In an effort to save Hope, Ryn and Ben confront Tia in an undersea battle between the mermaid tribes; Maddie and Robb work to find a cure for Xander; Helen and the hybrids help restore order.
Stars: Alex Roe, Eline Powell, Fola Evans-Akingbola
Director(s): Joe Menendez
Writer(s): Eric Wald, Dean White, Emily Whitesell