The full moon rises, and with the planets lining up, it can remove mermaid powers for good. Knowing this, Lewis lures Charlotte to the moon pool but it backfires and Emma, Cleo and Rikki could lose their powers.
Cleo is bullied by Charlotte and runs away to the ocean. With Cleo missing, everyone becomes more and more worried. Lewis discovers what Charlotte has been up to and breaks up with her. He finds Cleo and they kiss.
Charlotte takes over and organises 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.
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.
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. Ominous signs.
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!
Ash comes close to finding out about Emma. Meanwhile, the girls discover that Charlotte’s grandmother was Gracie. Old wounds open up for Charlotte and she finds part of Max’s research: an old movie of Gracie – as a mermaid!
When Zane and Ash clash at the juice bar, Rikki and Emma take their boyfriend’s sides. Cleo is left alone celebrating their one year anniversary of becoming a mermaid – until Lewis arrives just in time to help.
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.
Lewis has a bad dream about mermaids being discovered. It threatens to come true when Elliot asks Kim out on a date to the marine park and Cleo finds herself in trouble underwater in front of a crowd of people.
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!
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.
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 starts acting weird after pricking her finger on a barb of coral. Cleo's fish Hector exhibits the same behavior. Emma becomes more and more like a fish and Lewis has to find a way to cure her.
Zane hears of a treasure under the ocean and enlists the girls to find it. Rikki is injured in the search. Zane gives Rikki’s dad the $10000 reward. Charlotte contrives to keep Lewis from the girls.
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.
Lewis finds out about Cleo and the girls' experiment...
The girls reconcile their differences over what happened at the moon pool, and become closer.
The girls do some research on the impending comet...
Cleo offers her help to aid her father's wedding, but Kim still acts standoffish.
When Will follows Rikki to the moon pool, he sees something he wasn't prepared for.
With a little help from Will, Cleo is able to put on an amazing dolphin show!
Are Lewis and Charlotte an item??!
It's hard to keep up when you don't have a tail to help you out. Zane's finding this out the hard way.
Will, Bella and Cleo are beginning to worry about Rikki and her secrets...
With Bella's secret out, Will thinks he understands her, but is being a mermaid all he needs to know about Bella?
The girls find Will in Mako Island and try to keep their secrets hidden...
Will Lewis take the fall for the girls' prank?
Miriam's out to make Rikki's life miserable!
Cleo wants Lewis to just leave her alone!
Bella goes off on Will about leading her on, only to find out she's made a big mistake...
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