The famous rock band The Paperback music is convened for a big concert at Big Depression. Arriving at their destination, no musical event seems ready for that day, but suddenly a secret passage opens to the planet Planio, where dictator Balthazar has banned all kinds of music.
The archenemies of the Winx Club, the Trix witches, team up with the evil nymph Politea and find out that, to defeat the fairies once and for all and become invincible, it takes very little: a Pearl hidden in the Deep of the Infinite Ocean! As small as powerful, the Pearl of the Depth gives enormous powers to those who possess it! For the Winx there is not a minute to waste: how will they stop the plans of their enemies before it's too late? Get ready: the most dangerous mission of the Winx is about to begin!
