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Under the influence of a Full Moon, the girls' powers are hugely enhanced and they wreak havoc on Lewis in his boat. The next day the girls realize they still need Lewis.

Emma uses her new powers to help Elliott win at soccer. Lewis decides to test the girls' increased powers. Cleo has had enough of Lewis' smothering and dumps him. Lewis meets Charlotte and they bond.

Zane's back in town and still in love with Rikki. He works out she's still a mermaid and tries to win her back. Cleo becomes suspicious of Lewis spending time with Charlotte.

Rikki comes to stay at Emma's house and stirs up the family unit. In trying to compete with Rikki, Emma tries to rebel and throws a party. Nate uses Lewis to make a play for Cleo.

Lewis finds an old book on mermaids and tests out a potion recipe on the girls. Cleo tries to get Don and her Mom together by using her powers to grant him a wish. Realizing it's not what he wants, she finally accepts the situation.

Don appears to have a girlfriend - Cleo is shocked to find it is Charlotte's mother. Lewis becomes aware of Charlotte's feelings for him.

Everyone is shocked when Cleo is fired at the Ice Cream Stand, and even more so when Lewis takes her place! Rikki and Emma strike back at him but end up going too far.

Zane has an argument with a man in a trailer park but little does he know it's Rikki's dad. Rikki has to overcome her shame about her background and introduce her dad to Zane.

Emma meets Ash - a handsome horse riding instructor. A horse falls ill and Emma must use her powers to fix it. Lewis accidentally invites both Charlotte and Cleo to an awards dinner.

Cleo is failing at school and is assigned a tutor - Charlotte. Cleo wants Lewis back but her attitude to Charlotte only drives him further away. Cleo discovers Lewis and Charlotte kissing.

In need of cash, Rikki decides to go and searching for a lost statue with a huge reward.

Emma gets poisoned after cutting her finger on some coral and begins to turn into a white scaled monster!

Don takes the family camping on Mako Island during a Full Moon. The girls are affected and need the moon pool for sanctuary. Charlotte almost slips in the moon pool and realizes something weird is going on there.

Emma thinks she's going to get a promotion at the juice bar but Ash is given the job. Emma and Ash clash over the job, but we discover it's over a lot more. Meanwhile, Lewis stands up to Charlotte over spending time with Cleo.

Lewis and Zane find an old myth about mermaids is true: the scent of ambergris sends them wild. But it backfires when sleazy Nate gets hold of the scent and has all three mermaid girls on his arm!

Rikki tries to avoid Zane when he comes back, but needs his help after an incident with a speedboat. Meanwhile, Charlotte continues to flirt with Lewis and Cleo worries for their secret.

Cleo and Rikki push Ash into asking Emma out again; little did they know he'd turn up at Emma's place in time for a full moon! Rikki and Cleo are both moonstruck and Ash looks set to discover Emma's secret.

For the first anniversary of the girls being mermaids, Cleo decides to throw a party. However, Emma and Rikki fall out following a fight between Ash and Zane, and Cleo may have to celebrate alone.

Lewis discovers someone named Max Hamilton did research fifty years ago on the strange properties of Mako Island. Lewis tracks the old man down and finds that he knows a lot more about mermaids than Lewis first thought.

Charlotte demands answers to why Lewis is hanging out with the girls so much. She starts to believe an excuse from Cleo, but then a discovery from inside Max's research brings her to the secret! Meanwhile, Ash decides to help Emma with her "fear of water."

Charlotte follows Lewis to Max Hamilton. Max tells all to Charlotte when he discovers she's the granddaughter of his one true love. Charlotte and Lewis almost break up until she goes to the moonpool, becoming a mermaid herself!

The girls have to deal with a fourth mermaid who turns out to be a loose cannon; Charlotte almost turns into a mermaid at a volleyball competition. Charlotte discovers she has all three mermaid superpowers.

As the girls continue to have problems accommodating Charlotte as a mermaid, Nate bullies Lewis. Despite the girls' attempts to keep Charlotte under control, she uses her powers on Nate and almost exposes them all.

Charlotte takes over and organizes a surprise party for Lewis, annoying Rikki. At the party, Charlotte is jealous of Cleo and traps her and Emma in a pool room. Rikki comes back just in time. From now on, Charlotte is on her own.