(From the teaser trailer)
I think this movie has a different idea of story, if あなた compared it with some 前 バービー movies. And I'd like to share my idea about the story, as I don't find any plot of it.
Barbie starred as an astronaut girl, that exploring the 宇宙 with her team. But suddenly there was damage to their spacecraft and they were forced to landed on an unknown planet.
The planet was very similar with Earth, with beautiful forest, nature, and animals. They are also meet with the residents and befriend with them. There is a hidden magic 星, つ星 that keeps the planet alive.
But when the evil peoples want to ストール, 盗んだ the magic 星, つ星 from the planet, バービー and her team tried to protect this planet, for their familiar friend.