Madison's magic mirror transports her to a pool party.
Madison finds herself being hit on by a hipster, until he finds out she has a tail-fin.
A man tries to hook Madison up with his friend and his perfect legs.
A waiter stranded in the desert is visited by a magical mermaid.
After Nat discovers a party in a washing machine, she finally finds a guy not interested in mermaids.
After meeting the man of her dreams, Madison's date is interrupted by an evil trio of mermaid hunters.
Madison tries to bring her sister to a human party, in an attempt to prove that people aren't dangerous. Meanwhile, the evil trio attempts their first abduction.
In order to prove to her sister that not all humans are bad, Madison tries to convince the party-goers to help with a beach cleanup. Valerie ends up kidnapped by Jed, Astrid, and Stanley.
The good trio's car breaks down on their journey to find Valerie. Meanwhile, Valerie attempts a daring escape back to the ocean.
Madison and the gang discover who kidnapped Valerie.
Will uses the "Best Friend Finder" app to help track down Jed before the evil trio can sell Valerie to a sushi restaurant.
Madison and the gang try to turn Stanley to the good side while Astrid and Jed struggle to sell Valerie to a black market fish dealer.
Astrid devises an evil plan to capture Madison and leave her gang stranded on a deserted island.
Will returns to help rescue the mermaids while they work together to defeat Astrid.
The mermaids go with Will to save the rest of the gang from a deserted island.
Stanley invites mermaid sisters Madison and Valerie to his house for a Christmas party. It's their first experience with a human holiday, but the party goes horribly wrong when Stanley's girlfriend arrives and the mermaids become convinced she's an evil crab person in disguise.
While hiking with Nat, Stanley recalls how, as a child, he was saved by a kind mermaid, which sparked a strong love for merpeople in him for years to come.
Valerie and her friend Nat must figure out how to get her mermaid sister Madison back from hyperspace. But that is only the beginning of their troubles.
After Madison loses her tail, she and her friends must find one of the five magical relics to turn her back into a mermaid before the Barnacle King can get to it. Meanwhile, Valerie explores a magical lagoon.
While Valerie must do all kinds of weird underwater magic to repair the mirror, Will takes Madison on a date, and the guys go out looking for a long-lost French oceanographer.
While Valerie travels to an ancient forbidden pool to find a magical rock, Madison and her friends must face a crazy sea captain on their quest for the immortal Chrono-fish.
After Valerie and Beatrice put the finishing touches on fixing the mirror, Madison must decide whether or not she wants to turn back into a mermaid. Meanwhile, an evil creature from the lagoon surfaces in the spa's pool.
When a mysterious, evil sea creature steals all the relics, the team splits up. Valerie travels back to the dark pool to find clues, while Madison and her human friends dress up Stanley to go undercover.
Valerie, Will, and Liam track the creature that stole the relics to the Santa Barbara sunken house, a mansion that has been under the sea for decades. However, they are not prepared to face who and what they find there.
Disguised as a sea cucumber, Stanley gains the Barnacle King's trust as they search for a mystical old clam while Madison, Beatrice and Nat follow close behind.
Madison, Beatrice, and Nat must save Liam, Valerie, and Will from a group of evil sea monsters, while the Barnacle King attempts to complete his wicked plan.
The Mermaids and friends must stop an malevolent sea god in order to reunite land and sea and to save the world.
Madison and Valerie are in trouble. Beatrice and Will must search for the Magic Mirror to find out what happened.
Madison and Valerie face their sea monster kidnappers as the humans embark on a quest to find their lost mer-friends.
Madison and Valerie must figure out what mermaid song will open the magic lock to the well of power while Jed pays some old friends a visit.
Madison, Valerie and the sea monsters come up with a plan to get a whale song into the well of power while the gang lands in Indonesia to begin their search for the mermaids.
Valerie must learn an ancient technique in order to open the octopus lock while Nat and Liam have to fight for a magic ring.
Madison and Valerie must battle Ronan and Petromey to unlock the next stage of the well of power while Stanley and Will look for the ghost of a mermaid to help them translate the magic ring.
The final lock has the Mermaids confused as the humans get closer and closer to finding the location of the lost Mermaids!
United, the Mermaids, humans, and sea monsters figure our how to open the final lock on the well of power, but something goes wrong!
In the season 4 finale, the mermaids, humans and sea monsters must unite to stop the magic well from destroying everything in its way!