Ben has a dream about Ryn. They're having sex, but then she turns into her mermaid self and drags him deep into the ocean. Maddie stayed with Xander and he wonders if Ryn can tell him about the merman who killed his father. Donna and the other mermaids take clothes right off of beach dwellers. They tell the sheriff who alerts others to be on the look out. Ben and Ryn and Maddie figure out Donna is looking for her and brought company. Donna and the others intimidateHelen and demand to know where Ryn is. Ryn and Ben meet Donna and the others at the center. Only then does Ryn realize they're there to kill her not bring her back. Donna freaks out when she realizes they're trying to kill her sister. She, Ryn and Ben are on the run from them. Ryn tells Ben that her ancestor married a human but when they had a baby he was so disgusted by how it looked he killed it. Then he drove her bsck to the ocean and killed so many mermaids the ocean was red with their blood. The mermaids think Ryn is tainted and too human after spending too much time with them, so they want her dead. Ryn wants to stay on land, and Donna understands that Ryn and Ben care about each other. Helen tells Xander to protect his mother because mermaids are on land. He takes his father's gun and ends up joining Ben and the others trying to kill the rogue mermaids. The sheriff arrests the merman but he escapes. He later throws a spear through the police truck and injured the sheriff's leg. Maddie joins her father and shoots back at the merman. A showdown takes place in the streets and at the shipyard. Ryn asserts herself and the merwoman surrenders. Ryn is the alpha mermaid now. She sends both mermaids home, but Xander wants vengeance. He tries to shoot the merman who killed his father, but Ben tries to stop him and he shoots Donna instead. Xander is taken in to sleep in the drunk tank. They take Donna to Helen's but nothing can be done. She's dying. Ben calls Decker because he had Donnas cells and could probably help. Maddie tells Ben she doesnt know what's going on with him and comments on his bad judgment. They're fighting and she said she'd come back to check on run but she's staying with her father. The sheriff says the mermaids don't belong there, but if he has to pick a side, he'll fight for the town.