Stella and Brandon fall into an underground river at the bottom of the chasam which sucks them down the current into a whirlpool and onto the shores near an underground kingdom called Downland where they are found by a palace guard and a centry named Sponsus who takes the couple to Amentia the perfectionist and queen of Downland. Amentia quickly sees Brandon and literally takes him for her bride! A devestated and weakened Stella must soon find the sun or her friends will become monster chow!
Sky and the Specialists invite the Fairies to a grand opening party at the Red Fountain School. There, Flora meets the handsome poet, Helia. But while everyone is at the party, the TRIX sneak into the school. The Specialists and the WINX Fairies end up working together in the fight of their lives against Lord Darkar's biggest Shadow Monster yet.
Tecna becomes suspicious of professor Avalon when he starts making promises to all the girls on campus and appearing in more than one place at the same time. Tecna and Digit start to investigate on his past with some help from the other girls and they believe he's a powerful evil creature known as the Angel of Doom, who destroys realms by gaining people's trust, especially when he puts a spell on Bloom.
While Red Fountain is attacked, the witches break in and tries to steal the codex. Bloom, Flora and Techna tried to help the specialists prevent the witches from getting the codex but they did not succeed. Meanwhile, Sky is put under a deep sleep and later saved by Bloom
Sky, Bloom, Brandon, Flora, Lockette, and Zing attempt save Princess Diaspro from a band of goodie goodies known as the Wrong Righters who attempt teach Diaspro a lesson in kindness and helping others.
Bloom and the other WINX Fairies are trying to defend the Cloud Tower School for Witches from the evil TRIX. However, the WINX are split up, and each girl's weak point is revealed. Then the TRIX find a way to control Cloud Tower itself, turning the entire school into an evil monster!
Avalon once again meets up with Bloom and shows her a way to find more in her power by going through a magical regression journey. But this makes Bloom become evil when she transforms, and eventually makes Bloom want to steal Alfea's Codex! Will Bloom do it or will the others prevent her?
Bloom feels so bad, the fact that Icy put a spell on her to make Bloom get Alfea's Codex to Darkar. She's also worried that they have to fight Darkar soon. And that they're arguing so much. Ms. Faragonda says that if this happens, they'll lose to Darkar. She tells them that they have to remember why they called themselves the Winx Club. So the group gets to go on vacation to the Resort Realm, but the girls' Winx won't work there. The boys also have to go with them, it's their assignment, and they can't talk to them. Meanwhile Avalon gets hit by a poisonous flower, and...
To activate the Emperor's Throne, Tritannus must obtain the seals of the throne's missing pillars. When he takes the seal from the Pillar of Light, the planets are shaken, and it is up to the Winx to restore order.
The magical universe enters its darkest hour as Bloom (who has turned evil) and Darkar(who has dumped the witches) combine powers to enter Realix. The Winx girls and warriors circle Shadowhaunt with two aircrafts but eventually the Winx Club(minus Bloom) destroy all the monsters magical strength. And enter Shadowhaunt where they face Kerbog who has been yet again transformed into an extinct magical creature called an Octaceraton! The five fairies powers have no effect on it and when the Teachers show up and fail. Is there any hope of saving Bloom?
Just when a monster was about to hit them, the Winx girls got saved by Faragonda, Griffon, and Codatorta. Athena, Discorda, Ninfea, and Concorda, the Pixie Elders, are also there so they follow the Winx Club. However monsters attack them so Layla and Stella head for Realix first, then the others. Icy, Darcy and Stormy use their powers to combine and turn into MegaTrix and they take on Darkar. Bloom is about to summon the ultimate power, but Sky says words from his heart, saying that he loves Bloom. She is able to fight back the darkness, and come back to normal, ...