In this animated movie, Barbie (Kelly Sheridan) wants to teach her little sister, Stacie (Chantal Strand), the true value of friendship. So she and her best friend, Teresa (Cassidy Ladden), weave a music-infused fairy tale about Liana and Alexa, two peasant girls who have little else but each other and their love of song. When a magic mirror reveals an evil plan to destroy the Diamond Castle and end all music worldwide, Liana and Alexa bravely set out to save the day.