Mermaids

Mallick and Carlo are fishing with soda bombs in open water when they notice a large creature thrashing beneath the surface and Mallick fires at it, revealing a merman. They attempt to recover the body, but a powerful force knocks their vessel and a figure with a trident appears in the water. Terrified, the two men escape, leaving the merman's body behind.

Diana, the merman's eldest daughter, buries her father's body after the attack. She resolves to go onto land to seek help from her sisters Venus and June to pursue Mallick and seek justice. She sets out to find them, leaving the underwater world behind.

Venus works in a cafe and performs in a tank with a fake mermaid tail. Diana searches for her on land and finds Venus, who is appalled by her sister's behavior and suspicious of the motive behind performing for humans. The sisters prepare to unite but must convince June to join.

June has lived among humans for three years and works at a sea park. She is in love with Randy, who has a girlfriend named Cynthia, creating a complicated love triangle. The sisters realize they must set their differences aside to help each other.

Despite differences, the three sisters decide to band together to find Mallick and avenge their father. They plan to track him down and stop his illegal fishing operations. They convene on land to discuss their strategy.

Randy boards Mallick's boat in search of evidence and confrontation. Mallick and Carlo knock him unconscious into the sea, forcing June to rescue him and drag him to shore. The rescue reveals Randy's vulnerability and ties him closer to June.

Randy, unhappy with Cynthia, begins to fall in love with June. The new romance complicates their attempts to keep mermaid secrets and the investigation against Mallick continues.

Diana discovers Venus is forced to work in the cafe because Earl Barker has seized Venus's pearl tiara, her birthright of magic. Diana compels Barker to give back the tiara and also finds a large seashell that is the birthright of another mermaid.

Venus realizes the shell belongs to Betty, Barker's wife, who has forgotten her mermaid heritage. Venus returns the shell; Betty decides to stay on land because she has a human daughter.

The sisters learn Mallick has found their father's body and is keeping it in a freezer, and that he expects them to fetch a chest of sunken treasure to grant a wish. They agree to help, but they craft a plan: Venus retrieves the gold, Diana recovers their father's body, and June asks Randy to help, inadvertently revealing her true mermaid identity.

June reveals she is a mermaid to Randy, who accepts and remains supportive of her secret. The alliance strengthens as they prepare to execute the plan.

During the heist, the sisters deliver the gold to Mallick, and law enforcement arrives at the warehouse. The freezer is checked and discovers the merman's tail has dried into legs, revealing the murder. Mallick is arrested for murder as justice is served.

June worries that Randy is ignoring her, and Venus confesses she used a siren ability to make him forget the recent events to protect their secret. June chooses to stay on land in hopes of a second chance with Randy. Diana decides to stay on land as well to watch over her sisters, signaling a future of shared adventures.