Charlotte follows Lewis to Max and finds about about the truth about her grandmother. While on Mako island, she also witnesses Cleo, Rikki, and Emma in their mermaid forms. And finally, as it was the night of a full moon, she finds herself at the right place at the right time and becomes a mermaid herself.

Emma cuts a finger on a coral and starts acting very strange, like an actual fish.

Rikki's dad is having trouble paying the rent and is considering moving more inland, which prompts Rikki to accept Zane's offer to retrieve a stolen idol at the bottom of the ocean for a reward money.

Lewis and the girls brew a magic potion which lets Cleo grant wishes. But things get out of control when Rikki adds a bit of heat to it.

Cleo is being jealous at Charlotte because Lewis and her spend a lot of time together, but bottles it down and pretend she concerned about their secret while in front of Lewis. Zane is back in Rikki's life and the two of them start dating again.