Barbie and the Diamond Castle (2008)

To understand the importance of friendship, Barbie and her best friend, Teresa, decide to tell young Stacie a musical fairy tale of a hidden beautiful land, and two kind-hearted girls who love music: Alexa and Liana. As an enchanted mirror paves the way for a wonderful new friendship, the two companions embark on a dangerous quest to the sparkling Diamond Castle, to thwart the secret plans of the malevolent muse, Lydia. Can the power of love and companionship save the day?