本片的故事也將首度揭露 Ariel 的母親 Athena 皇後，Ariel 才剛剛出生，母親就遭逢意外，傷心難過的 Triton 國王下令禁止任何的音樂，整個王國從此沈寂了好長一段時間，直到 Ariel 到了她那愛冒險的年紀，在初次相識的小比目魚帶領下，Ariel 來到海底居民的地下聚樂部，原來大家都在這邊勁歌熱舞同樂，連宮廷大臣 Sebastian 也不例外，Ariel 還把姊姊都一起帶來玩，但秘密終究還是無法永遠隱藏，告密者已經向國王通知，Ariel 要如何撫平父親記憶中的傷痛，讓優美的旋律重返海底世界呢？

　　Every story has a beginning but only one begins under the sea now for the first time ever discover the story you never knew in The Little Mermaid. Long ago in a kingdom where music is outlawed King Triton s youngest daughter Ariel discovers her love for music in a secret underground music club. Torn with the choice of whether to hide her passion or share it with her father and risk losing everything Ariel sets off on a daring adventure to restore music to Atlantica.