Everything seems to be peaceful at Alfea, where the Winx are working as tutors for the freshman fairies, but the wicked Trix, the Winx archenemies, arrive at the Infinite Ocean with the intention of conquering the Emperor's throne and power. Human beings are in fact polluting the oceans, putting at risk the balance and the ecosystem of the Infinite Ocean, the dimension that connects all the seas of Magix. This presents the Trix with the perfect opportunity to attack and become empresses. But the brave Winx aren't about to just sit and watch as the y underwater worlds are being destroyed! Will their courage and purity be enough to restore the balance of the Infinite Ocean, fight pollution and bring peace back in the Magic Dimension? ..