Barbie stars as Corrine, a seventeen year-old country girl who dreams of becoming a Musketeer, one of the protectors of the royal family. There is just one problem: there has never been a female Musketeer before, but that isn't going to stop Corrine. In search of her dream, she travels to Paris with her cat Miette and a letter introducing her to Monsieur Treville, the head of the Musketeers. However, a grumpy old dog makes off with her letter and while she chases after him, she is unsuccessful in getting it back.
Along the way, she meets three other girls - Viveca a fashionista, Aramina a dancer and Renée an violinist. All four girls are soon employed as maids at the royal palace, where they all realize they share the same wish to become a Musketeer.
When a wise old woman notices their fencing and athletic abilities, she takes them to a hidden chamber in the palace and helps them train and develop their unique talents. However, Corrine and her friends soon discover a plot to get rid of Prince Louis at a royal masquerade ball and they realize that it's up to them to save him.
The main line in this story is "All for one & and one for all".