The vision reappears to Mimi and Zac, this time speaking to them. Weilan learns a new detail about the dragon legend that suggests Nerissa is alive.

A priceless artifact recovered by a deep-sea treasure hunter provides a clue as to how the mermaids can defeat the water dragon.

Sirena, Lyla and Nixie must turn Zac back into a land boy. Using Sirena's Moon Ring, they give themselves legs and walk on land to begin their task.

In trying to get the Moon Ring back, the mermaids uncover Rita's secret.

While listening to Sirena sing, Lyla has an idea. If Sirena sings The Enchantment Song to Zac, he will fall under her spell. Everything goes south when David hears the song and falls in love with Nixie.

Lyla and Sirena attempt to use the Moon Ring to stop the rain, but instead make it snow indoors.

After finding a Moon Ring on the sea floor, Zac gives it to Evie. Now, the mermaids must get it back.

Cam gets a new phone and films Zac swimming.

Nixie and Sirena won't help Lyla try to "zap" Zac's powers, so Lyla decides to do it alone. This misfires when a waitress spills a drink on Lyla and Lyla rushes to hide in the refrigeration room before she transforms into a mermaid! When she can't dry her tail, Nixie and Sirena must save her before she is discovered!

It's a full moon and the mermaids think that if they keep Zac out of the moonlight, he will lose his powers and return to his land-dwelling self. They stay with him in his garage on the full moon and attempt to keep him indoors.

Zac's struggle with his merman secret intensifies when his girlfriend, Evie decides to throw him a pool party.

The chamber's true purpose is revealed: to drain the magic from all mermaids. Zac risks his life to shut it down and restore the mermaids' magic.

Zac starts to wonder why their principle, Rita, is helping Lyla, Nixie, and Sirena.

When Mimmi loses her moon ring in the Ocean Café's cooler room, it creates havoc for David and his brother's business.

With the full moon approaching, Zac's plan to avoid Mako Island is dealt a blow when his father insists they go on their annual camping trip.

It's a full moon and the three mermaids Nixie, Lyla and Sirena are tasked to guard Mako and the moon pool. While Zac and Cam go camping on Mako island. When Zac falls into the moon pool they don't know what to do and leave him on the beach. The next day Zac finds out what he is and what he can do so he tells Cam. Because the girls let the "land boy" as they call him in the moon pool they are being cast out by their pod. So they decide to fix the problem.

When Evie comes down with a fever that causes the temperature in the room to soar, Carly suspects that her friend is keeping a secret from her.

Zac is being watched by the mermaids, but with Cam's help he evades them.

After acquiring the Trident, Zac doesn't know how to turn it on.

On the night of the full moon, Zac and Erik swim to Mako Island and unlock the merman chamber, revealing a startling secret.

Ondina doesn't want to choose between Erik and the pod when the pod returns. To cheer her up, Erik decides to throw a party in the café.

When Sirena sees a video that shows a kayaker being lured by a mermaid's song, she starts to follow David obsessively, and he falls under her spell.

While Ondina teaches the little mermaids to walk on land, her fastest-learning student wanders off and soon runs into Chris and Karl on the beach.

Rita's cat is turned into a human after walking through a bunch of mermaid powders.

Zac struggles to come to terms with the news that he's a real merman, he's adopted and Mimmi is his sister.

When Mimmi and Chris go on a date at the beach, Ondina goes to great lengths to protect her. Cam tries to lure more upscale customers to the cafe.

Aquata returns saying Sirena can come back to the pod, but Lyla and Nixie can't.

Nixie agrees to help Cam unlock the Trident, but Evie wants to come along.

Zac realizes a shell he found has magical powers, and he accidentally sends the mermaids back in time five years, where they meet his younger self.

When Erik dives down and touches one of the rock outcrops on Mako reef, he's transported into a sphere of endless water with no way out.

Ondina sneaks Erik into the grotto to duplicate a pearl he gave her, but she accidentally turns him into a copy of Poseidon.

Zac must find a place to hide the Trident from the Mermaids.

When the pod decides Zac is a threat and must give up his merman powers, two new mermaids, Mimmi and Ondina, are sent to make sure he obeys.

Sirena gives Evie mermaid lessons, which rubs Ondina the wrong way, while Erik tries to get to the bottom of Zac and Cam's falling out.

At the marine park, Ondina and Mimmi get into trouble when a dolphin splashes them and a little girl sees them transform into mermaids.

When Erik learns that the trident stone is the missing element needed to activate the merman chamber, Zac gives it to the mermaids for safekeeping.

Zac begs Weilan to teach him an Eastern spell few have mastered, which he hopes to use against the dragon. Joe encounters a water ball.

Weilan mistakenly makes tea for Rita using a magic growth accelerator. Can the mermaids cure Rita before Mrs. Trumble takes over her principal job?

After overhearing Ondina blaming her for Evie's loss, Weilan runs off. Meanwhile, Mimmi and Ondina combine their powers to try to restore Evie.

When Zac has a powerful vision about his connection to Mako Island, he and the mermaids visit the island to investigate.