Emma, Rikki and Cleo think they fooled everyone who discovered their secret into thinking they lost their powers. Only Lewis knows they’re still mermaids. Life is back to normal for the girls, they go swimming on the underwater reefs, shop for the latest clothes – and avoid getting splashed with water. After all, no-one wants to grow a mermaid tail in public! Life radically changes on the next full moon when the girls are hit with super strong moon blast that sends their powers out of control.

Lewis is almost hurt as the girls struggle with their powers over water. However, with enough practice they do eventually learn to control them. But it’s an eerie question: why have their powers increased?

Charlotte starts school. She’s smart, ambitious, and immediately finds Lewis attractive. The only problem is he’s going out with Cleo. Not for long. While learning how to control their new powers, Lewis won’t leave the girls alone and smothers Cleo. She can’t handle it anymore and reluctantly breaks up with him. Lewis is devastated but Charlotte quickly takes her opportunity to spend more time with Lewis. They connect. Soon, Lewis finds himself torn.

Along the way the girls have a lot to deal with: from magical mermaid myths about wish giving and love potions to more everyday problems like dealing with your family. One thing rises in importance; fifty years ago there were three other mermaids. And just like Lewis knows about our girls, there was a boy who knew about them – Max Hamilton. Lewis tracks Max down and finds he knows a lot about mermaids, especially the one who was his one true love: Gracie.

When Gracie is discovered to be Charlotte’s long lost grandmother, everything changes. Charlotte had a short but very close relationship with her and she is driven to find out everything about Gracie. Lewis tries to waylay Charlotte and their relationship is on the brink when she discovers he’s been covering up the truth all along – her grandmother really was a mermaid.

Charlotte finds the moon pool – and becomes a mermaid! Emma, Rikki and Cleo take Charlotte in as the fourth mermaid but it is clear this can’t last. Soon all the planets line up to form the biggest full moon event in history. Finally Emma, Rikki and Cleo discover the answer to why their powers increased.

And they’re going to need all the help they can get.

Cast
Cariba Heine as Rikki Chadwick 
Claire Holtas Emma Gilbert
Phoebe Tonkinas Cleo Sertori
Angus Mclaren as Lewis Mccartney
Brittany Byrnesas Charlotte Watsford
Burgess Abernethy as Zane Bennett 
Craig Horneras Ash
Jamie Timony as Nate
Cleo Massey as Kim Sertori
Alan David Lee as Don Sertori
Trent Sullivan as Elliot Gilbert
Jared Robinsen as Neil Gilbert
Caroline Kennison as Lisa Gilbert
Andy Mcphee as Terry Chadwick
Tiffany Lamb as Annette Watsford
Martin Vaughan as Max Hamilton 
Ariu Lang Sio as Wilfred