The Little Mermaid: Ariel's Beginning

King Triton and his wife, Queen Athena, rule over the underwater kingdom of Atlantica, filled with music and laughter. They have seven young daughters: Attina, Alana, Adella, Aquata, Arista, Andrina, and Ariel. One day, while the merpeople relax in a lagoon at the surface, King Triton gifts Queen Athena a music box. However, the merfolk flee at the approach of a pirate ship. Everyone escapes except Athena who, while trying to recover her music box, is killed when the ship crashes into the lagoon. Devastated by her death, Triton throws the music box away and bans music from Atlantica. He also bans any of his subjects from going to the surface again.
Ten years later, Ariel and her sisters live under a strict routine maintained by their governess, Marina Del Rey, and her kind hearted assistant, Benjamin the manatee. Marina hates being the girls' governess and longs to be King Triton's attaché, a job currently filled by Horatio Thelonious Ignacious Crustaceous Sebastian the crab. Ariel is equally frustrated by her and her sisters' dull lifestyle, which causes arguments with her father and drives a wedge between the two.
One day, Ariel befriends Flounder, a young tropical fish whom she later follows to an underground music club. She is overjoyed by the presence of music and is shocked when she sees Sebastian performing there. When her presence is revealed, the entire band stops playing and hides, believing Ariel will tell her father about them. Instead, Ariel is moved by her mother’s memory and sings I Remember, recalling the joy that filled her family’s life when music was a part of the kingdom. She is accepted as a member of the club after swearing an oath of secrecy.
Ariel returns to the palace and her sisters confront her over her disappearance, she explains where she was and, the following night, all seven princesses go to the club and have fun. However, Marina follows them, discovers the club and later reveals its existence to an angry King Triton, who destroys the club. He imprisons Sebastian, Flounder, and the band and assigns Marina to take over Sebastian's duties while Ariel and her sisters are confined to the palace as punishment for their disobedience, but she gets into an argument again with her father, who losing his temper and saying that he will not have music in his kingdom, which horrifies Ariel.
Unable to live in the kingdom without music any further, Ariel decides to runs away from the palace and frees her friends from jail. Although initially against the idea, Sebastian leads them to a deserted place far away from the palace where Ariel discovers her mother's music box, as Sebastian hoped. Ariel realizes her father has forgotten how to feel happy since Athena's death and decides to bring the music box back to him, hoping it will remind him. Meanwhile, Attina informs Triton that Ariel and Sebastian have run away and he orders his guards to find them. Knowing that Triton is regretting his hasty dismissal of Sebastian and desperate to hold onto her newfound power, Marina releases her electric eels to hunt down and kill Ariel and Sebastian.
Ariel and the band are confronted by the eels on their way back, but Flounder defeats them. Sebastian and Marina fight, but she is apparently defeated when he traps her in a coral tube. However, just as King Triton arrives, Ariel notices Marina barreling towards an unaware Sebastian, intent on killing him. Triton watches in horror as Ariel rushes to protect Sebastian and takes a very hard hit, knocking her unconscious as she falls to the sea floor. As Triton dives down and holds Ariel, he blames himself for the lack of joy in the kingdom; upon hearing the music box play, he sings to Ariel, who revives. Triton apologizes and the two reconcile.
Following this, King Triton lifts his decade-long banishment of music and welcomes it back into his kingdom, much to everyone's delight. Sebastian is reinstated as right hand to the King, as well as appointed as Atlantica's first official Court Composer. Marina is imprisoned in the dungeon for her crimes, Benjamin becomes a prison psychologist, and Ariel shares a dance with her father.