Barbie & the Diamond Castle is a 2008 American-Canadian animated movie based on the popular children's toy created by Mattel. It was the thirteenth direct-to-video animated Barbie movie to be created by Mattel. In the film, the character Barbie tells a story about two friends, Alexa and Liana, who try to keep an evil muse from destroying all music.
The evil muse Lydia uses her magic flute to hypnotize Alexa into revealing the location of her friend Liana, so that she can be captured as well. Lydia retrieves the magic mirror in which Alexa and Liana's friend Melody is hiding, but when Melody refuses to cooperate, Lydia orders the hypnotized Alexa to walk off a cliff into a pit of acid.