Sci-fi version of “Little Mermaid” where Ariel is a genetically engineered mermaid who is part of a top secret military program (Atlantica). She is capable of sinking submarines and ships with a powerful sonar she is able to create with her underwater voice. She is ordered to sink a fishing vessel (mistakenly thought to be a foreign military vessel) in the Pacific Ocean off the coast of Los Angeles. She saves the Captain (Eric) but becomes depressed about her situation of destruction and lack of legs. Of course, she’s smitten by Eric and wants to be with him on land.
Eric’s father happens to be the Admiral who has Project Atlantica under his budget. Once he hears of the incident, he decides to shut it down. The program director (Dr. Triton) is told of the news to shutdown the program and is ordered to euthanize all of the creatures in the program. Of course, he has to keep it a secret, but the AI running the facility (Underwater Research System – Los Angeles) discovers the plan and uses Ariel’s love of Eric to coerce her into becoming a bipedal land dweller.
URSLA sends an AI lobster bot (Sebatian) to make arrangements with Ariel to become bipedal. URSLA fabricates some bionic legs to allow Ariel to see the world through a bipedal experience. Of course, Ariel must do a favor within 72 hours for the URSLA AI by plugging in a blue and yellow device (Flounder) to the USB port of an specific computer (Admiral who is shutting down Atlantica/Eric’s father).
Since Ariel is an underwater creature, she cannot vocally communicate outside of water, and there is not enough time to create a vocal communicator for her. The AI hides her from Dr. Triton but doesn’t let on that it knows Dr. Triton is euthanizing all the creatures and allows them to be systematically killed, including others just like Ariel.
Meanwhile, Ariel gets Eric to fall in love with her via online dating apps and virtual reality, masking her lack of voice. She gets to meet Eric’s father after Eric invites her to have dinner at the Admiral’s house. There she discovers that the URSLA program is slated to be shutdown by Eric’s father because of the incident where Ariel sank Eric’s ship, killing everyone aboard. This is only after she has already plugged in the device to the USB port.
The URSLA AI spreads to a nuclear submarine and begins to move the submarine into the Pacific to initiate global nuclear war. The only one who can stop it is Ariel, but since she no longer has fins, Eric must take her in an old ship, under heavy weather, and drop her into the ocean where she can destroy the submarine. She will have no way to make it back to the surface without fins, but it’s the only way to save Eric and humanity!