Two young mermaids, Ondina and Mimmi, run away from the Mako Island pod with Sirena to try to turn the merman Zac back into a land boy. But Zac's connection to Mako is growing stronger. If they fail, they may never break his connection and save Mako for the pod. On the full moon, they attempt to remove his merman powers when his girlfriend Evie comes to the rescue - only to be turned into a mermaid.