Now that he knows Sirena, Lyla, and Nixie are mermaids, Zac starts to wonder why his school principal, Rita is helping them. Meanwhile, Rita begins giving the girls lessons on how to use their powers. Zac soon discovers that Rita is also a mermaid and decides to use this knowledge to his advantage. With her cover blown, Rita tells the girls she must leave town before Zac exposes her. The girls decide to fight back by using their powers to disrupt Zac's life and nearly expose him in front of Evie.