Feature-length episode of the children's animation following the little girl who became a princess after her mother married the king of Enchancia. Sofia (voice of Ariel Winter) runs into trouble when she gets the chance to turn into a mermaid and visit her new underwater friend Oona (Kiernan Shipka). With the help of Princess Ariel (Jodi Benson), Sofia tries to prevent disaster both on land and under the sea. Also included are three additional episodes: 'Tri-Kingdom Picnic', 'Finding Clover' and 'Make Way for Miss Nettle'.