The Princess Miranda lives with her father, King of the Sea, and two sisters in a magical underwater palace. Miranda has the most beautiful voice of all the underwater kingdom, to the delight of all its inhabitants. The princess feels a great curiosity about the world above and why humans do not treat sea creatures with the same respect it. To celebrate its fifteenth birthday her father allows Miranda to see the human world with her faithful friend Acme, an otter. On the way to the coast the princess saves the life of a drowning man, a handsome young prince who falls in love.