Ariel wants legs so she can dance but no one believe's in her dream. She gets discouraged until she meets another mermaid called Gabriella who wants to sing so they go to a magical starfish who can make their dreams come true.
King Triton wants Ariel to learn how to play the calliope, but Ariel wants to learn how to play the harp. She tries to learn the calliope and her bad playing wakes up an old ancient evil sea monster.