So there's many mermaids and then theres three main mermaids named Sirena,Lyla and Nixie.So a mermaid named Aquata and she orders Sirena and Nixie to go gaurd Mako Island because its a full moon,Siren asks Aquata why can't they celebrate like all the other mermaids and Aquata says "You will,when you get your moon rings".So they hurry and go to that magic moon pool in Mako Island.So Lyla and Sirena meet Nixie in front of Mako Island and Nixie says "You're late".So then Nixie orders Lyla and Sirena to take the rest,while Nixie watchs the far shore.So they all swim off and then this boat with two boys arives,they try to catch a fish and they fail doing it.So then Sirena and Lyla pops up in the water and Sirena says "Land People,I can't imagine people living without a tail".So then Sirena just wants to get them away from Mako Island and she throws a fish up and one boy catchs it.The boys don't see Sirena and Lyla and just thought they caught a fish.So then Nixie pops up and she saw what Sirena did and has a look on her face.So then Sirena says "See,there now they will go back home".So instead the boat goes more towards Mako Island and the boat stops at shore.So then Nixie says "Doesn't like they're going home".So Nixie,Sirena and Lyla follow the boys.Then the boys find their camp and sets up their tent.So that night one of the boys named Zac went to find a place to pee.So after he pee's he see's a door apear near him and he goes into it.He see's this mark that's glowing,so he touch's it.Meanwhile Nixie,Sirena and Lyla are in the Moon pool cave.Their holding hands and laying back in the pool as the moon light hits over them.Then out of no where Zac falls into the cave from the ceiling and falls into the water.Then the moon light disappears and Sirena,Nixie and Lya hurry to help Zac out the water.Next thing you know Zac wakes up on the beach by the shore alone.He finds his camp spot and tells his friend what happened.His friend doesn't believe him and so Zac just says they should leave.So they leave and later on Zac realizes he can control water and try's to show his friend.Sirena,Nixie and Lyla are close by and control the water so it will look like the water isn't doing anything.So then later on Zac goes in the water and see's he has a tale and he calls his friend.Then his friend see's his tale and is so suprised .So meanwhile Nixie,Sirena and Lyla are in the moon pool trying to think if they should tell their mermaid people leader Aquata about what happened.So Aquata hears that and appears.She is upset and thinks it's their fault that the other mermaids are in danger now.So then Aquata leaves and the next day,Sirena's sister Aquata comes and tells Sirena,Lyla and Nixie that the other mermaids is leaving them and they can't follow them.So them Sirena begs for her sister not to leave them and she says she has to.So Sirena's sister gives Sirena her Moon Ring and leaves .Sirena cries and Lyla says "We're not going anywhere,we're going to put this right"Then that's the end of that episode.