Julie and Kaja are two adventurous sisters who spend the weekend with their mother's friend Agnès, who is a talented children's book author. When Agnès decides to take a nap, the girls discover a secret passage to the universe in their favorite book 'The Kingdom of the Wind'. But it turns out that they themselves are transformed into fantasy animals and trapped inside the fictional universe. To get back home, they must find Sirocco, a mysterious and powerful person who rules over the winds.