The series returns to the magical Mako pool where schoolboy 16 year-old land-dweller Zac forms a special connection with the island and is granted a fish-like tail and amazing powers after a moonlit swim.
The mermaid population flees leaving Lyla, Sirena and Nixie to go ashore who in a bid for survival must get legs, venture onto land and steal his powers back.
In the lead roles are Lucy Fry (Lightning Point, 암초 Doctors) Ivy Latimer (Me & My Monsters, 사랑 My Way) newcomer Amy Ruffle and Chai Romruen as merman Zac.
"The 인어 are back but they are real this time," says Shiff.
"They will come ashore and have all sorts of adventures, like learning to walk on legs and answering a telephone for the first time."