Barbie & The Diamond Castle - 2008

Barbie and the Diamond Castle is a 2008 direct-to-video computer-animated film that was released on September 9, 2008. The film features the voice of Kelly Sheridan, who has voiced the Barbie protagonist in the CGI Barbie film series. It is the third musical in the series.

The movie begins with Barbie and Teresa writing a song together on their guitars when Barbie's sister Stacie storms in, angry at her friend Courtney. Barbie decides to tell Stacie the story of two friends named Liana and Alexa, who also get angry at each other.

Although the two girls do not have much, they have each other, a love of music and depend on planting flowers to upkeep their living. They live in a hut beside a beautiful garden. One day, they find a pair of heart-shaped stones in the river near their house,not realizing they are actually trinkets of the mythical Diamond Castle. And they turn them into necklaces to symbolize their friendship. The next day, after sharing the last of their food with an old woman, she gives them a mirror, although none of them are aware that it is the hiding place of Melody, an apprentice muse on the run from Lydia, a previous muse who turned evil and changed the other two muses to stone, but not before they hid their home, the Diamond Castle, and left the key with Melody. As the Diamond Castle is the birthplace of all music, Lydia's finding it would mean the end of music, and with it, eventually the world. Liana and Alexa coax a song out of Melody by singing, and Lydia's minion, a dragon known as Slyder, is able to locate the young muse by her voice.

With their home destroyed by Slyder, Alexa and Liana head off with Melody to find the Diamond Castle and keep it safe from Lydia, finding two small puppies on their way. But with no food or money, they eagerly take the place of two musicians at an inn that evening. The musicians, twin boys named Ian and Jeremy, hear the girls play and sing, and instantly fall for them, but the girls leave them behind at the inn. No sooner are they out of the town than Lydia confronts them, using her magic flute to cast a mind spell on them, but the stones on their necklaces (originally from the Diamond Castle itself) protect them. Unable to use her magic against them, Lydia sics Slyder on them, and he nearly gets them, but the twins from the inn arrive on horseback, and the four of them give Slyder the slip..