The Winx try to obtain Mythix, but first they must prove themselves worthy of doing so. Meanwhile, the Trix boost their powers, but they don't allow Selina to bolster hers.
The Winx search for an emerald hidden in a pirate ship, which is in a fictional world called the Legendarium. Meanwhile, Selina sends the Trix into the same world.
A ship full of zombie pirates battle the Winx and the Trix, both of whom must exit the Legendarium quickly or become forever trapped there as characters within the book.
The Winx are determined to enter Cloudtower and lock the Legendarium. But plans are halted when Cloudtower becomes invisible! Meanwhile, Stella is queen for the day, but the power - and the Legendarium - have gone to her head.
In an attempt to get her crown back from Darcy, Stella faces off with a Minotaur in an ancient Labyrinth. When she finally escapes the Legendarium World, she must return to Solaria to right the wrong she has done as Queen.
The Winx travel to Zenith in hopes of finding a special technology that can track down the invisible Cloudtower. But Tecna's reunion with her family is interrupted when Frankenstein, sent by Selina, falls in love with Tecna.
Musa establishes the Alfea music café, and the Winx use the instruments' magic to protect Alfea from the flying Cloud Tower. But when Rumpelstiltskin steals Musa's voice, the Winx must get it back in time to ward off Cloud Tower.
Even without her voice, Musa uses music to save Alfea from the witches. But now the Winx must choose between Musa's voice and the Legendarium Key, which Rumpelstiltskin has offered to accept in exchange.
When the Trix challenge Bloom to a one-on-one duel with Selina, it is up to the Winx to provide backup. But when Selina unleashes the mighty, yet dangerous, champions of Alfea, all rules go out the window.
As the Winx prepare for Daphne and Thoren's wedding, they soon discover that Selina freed Acheron. Acheron banishes the Trix to the Legendarium and then removes all magic from the Magic Dimension - except for the dragon flame.
While the Winx battle the Great Lizard Spirit, Bloom fights Acheron and the Trix in the Legendarium World. The Winx need all the help they can get - even Selina's - to fight dark magic and restore order in the magic dimension.
Back to the present, the Winx organize the inauguration of the Alfea Natural Park, where now there are many Digmoles, saved by the Winx in the past. The Digmoles hide a mysterious enigma.