Now known for their heroics, the Winx must combat a new evil called the Wizards of the Black Circle, who are searching for the last fairy on Earth.
Another school year starts at Alfea. The Winx are very happy to return to Alfea, this time as teachers. When they enter the school, all the students express excitement to see the famous Winx. Everyone, except Stella does not enjoy the attention.
Faragonda, explains to the Winx that they now have a different room since they are now teachers instead of students. She then takes the Winx to her office, expresses her gratitude for their acceptance to teach, and shows them a secret room, the Hall of Enchantments.
She explains that the hall is like a history museum of magic, and gives them the Book of Fairies. She also tells them about a new, more powerful fairy level which they can acquire: Believix. Faragonda further explains that this is the first time in which the Winx can connect with people's hearts and influence their feelings. Bloom searches the room and finds another hall, a hall with pictures of past villains which Faragonda explains is the hall where the portraits of all the enemies of Magix are found. Bloom finds a picture of the Wizards of the Black Circle. Faragonda appeared frantic when Bloom reveals the covered portait of the Wizards, when asked who they were, Faragonda evades the question and tells Bloom she needs to rest because her classes start the next day.
Before entering the classroom, the Winx in front of the door, too nervous to go in. Tecna gives them a nice surprise, a virtual holographic chat with the Specialists to ease their nerves. Bloom is wondering where Sky is and Timmy sends her a message Sky left for her. Griselda reminds the girls to hurry and come in as their students are waiting for them.
They enter the classroom. After introducing themselves to the students, they provide demonstrations on how magic works as well as important advice that comes with learning about magic. All the students are diligent and excited while Clarice remains unimpressed. After that, they announce that they will do a hard obstacle course, to show how special Enchantix is.
As the students get situated, Clarice tells her friends that the Winx are just show offs, Alice defends them as they are Enchantix Fairies. Clarice does not care about that statement and decides to prank them with a fireball explosive, normally used for celebrations.
She sneaks off as Griselda and Faragonda tell the fairies to take their seats. She places it in the spherical course and then heads for her seat. As the show begins, Clarice places the box used to contain the fireball in Alice's bag.
Aisha, Bloom, and Flora do the course themselves. As Flora does the course she is stuck in an optical with a bomb-like object, which Clarice activates and it explodes leaving Flora unconscious. The Winx remain in the nurse's room with her, while Tecna determines the suspect who had activated the fireball to be Alice. For doing something so dangerous she is expelled. Flora, who recovered quickly after the incident, wants to talk to her, and looks for her.
Alice had just exited Alfea's entrance doors when she sees Flora searching for her when the Wizards of the Black Circle arrive at Alfea, in search of Bloom who they believe to be the last Earth fairy. Flora refuses to tell them where Bloom is, and they attack her. Alice witnesses everything and runs to the Winx trying to explain everything. Tecna and Stella do not believe her but they follow the others to find out what is happening.
The Winx transform and battle with the Wizards of the Black Circle, while everyone is watching. But The Wizards are being too strong against the Winx, defeat them. The Wizards then create a small portal with the Black Circle, trapping Bloom inside. However the portal rejects her as she is not the last Earth fairy. The Wizards seem disappointed, and then vanish into another portal saying that the hunt for the last Earth fairy is not over yet.
Now that everything is over, the Winx are in Faragonda's office expressing their disappointment, especially as role models for their students. Faragonda comforts them and the popularity should not judge the worth of a Fairy. Faragonda then tells the Winx to follow them as there is someone who wishes to say something.
Clarice is sitting outside Faragonda's office, when they step out she confesses that she was responsible for the explosion and apologizes. In the end, Alice and Clarice were not expelled thanks to Alice's plead to Griselda.
Back on to the matter at hand, Faragonda explains to the Winx about the Wizards, and that they will need to be more powerful in order to defeat them.
- The Winx return to Alfea as teachers.
- The Winx learn of the Believix transformation from Faragonda.
- The Wizards of the Black Circle arrive at Alfea, searching for the last fairy on Earth.
- The Wizards turn to Alfea to catch the last fairy on Earth, but are angered when they find out Bloom is not the one they were looking for and thus making it a wasted trip.
- Morphix Surfboard - Used to create a surfboard during the show.
- Nature Dust - Used to change fire in the obstacle course to flowers.
- Dragon Flame Power Fire - Used to hold the debris.
- Enchanted Plasma - Used against the Wizards of the Black Circle.
- Electric Storm - Used against Ogron.
- Magic Bass Boom - Used against Gantlos.
- Disco Shell - Used to defend herself.
- Dragon Energy - Used against Ogron.
- Fire Ray - Used against Ogron but failed.
- Sun Energy Burst - Used against Wizards of the Black Circle.
- Dragon Fury - Used against Wizards of the Black Circle.
- During the attack of the Wizards of the Black Circle, when all the staff and students of Alfea came to see what was happening outside, Professor Wizgiz made a reference to the Harry Potter book series by saying "Merlin's beard", which is a popular saying common to wizards in the Harry Potter.
- This serves as a continuity to Season 1 where in the second episode, Faragonda and Griselda comment about how they thought all the fairies on Earth disappeared long ago when Bloom told them she was from Earth (not knowing she was in fact from Domino at the time). The Fairy Hunters are that reason.
- In the Nickelodeon dub, this episode along with the next episode was part of the one hour premiere of Winx Club: The Power of Believix.
- This is the first episode animated with flash animation and digital ink.
- This episode was released on U.S.'s iTunes for free.
- This is the only time Griselda appears in the fourth season.
- Bloom is in the Great Book of Fairies as the Enchantix Fairy.
- As of this episode "Under the Sign of Winx" is replaced by "Winx Are Back" as the opening theme song, while "Superheroes" replaces "If You're a Winx" as the ending theme song.
- Starting this season, season three's Enchantix song is replaced by the song used in the first movie.
- Griselda told the Winx that the new students live in their former rooms and they will be living in new apartments for teachers, but in Season 5 they return to their apartments.
- It could be because they retired themselves from being teachers at Alfea.
- In one scene when talking with the Specialists, Aisha's top was missing.
- When Flora turns her head after Helia kisses her hand, she is missing her yellow streaks on her bangs.
- While standing next to the teacher's desk, Flora's missing her socks.
- As Clarice is sneaking behind the course, Musa is wearing lavender eye shadow.
- In the scene where Alice and Stella are helping Bloom up, Stella's Enchantix translucent pink gloves go right up to her shoulder and connects with her top.
- In one scene, the back of Tecna's hair while in her Enchantix went missing.
- In the scene after the Winx transformed into Enchantix, Flora was still lying on the ground and she was also in her Enchantix form with the Winx flying up.
- During the course demonstration, the audience has many of Alfea's students that are recolored or duplicated.
- In one scene, Karina shirt is colored incorrectly.
- In one scene, Aisha's Enchantix has her regular hairstyle
- Occasionally, Some of the Winx's wings will change opacity incorrectly
“Uh, who are you? This is our room!”
“No, it's not this is our room!”
“You're no longer students, girls! You'd better get used to the idea!”
“This was the Winx room?!”
“Exactly. Study hard and if you're lucky, you'll be just as good as them!”
“This, is the Great Book of Fairies. Read it and you'll see that each transformation leads to a change. New powers, new horizons!”
“There's a level up Enchantix called Believix. ... You have considerable powers. Because of your strength, you have become guardian fairies, guardians of your world. Your spells effect nature and technology but with the Believix power, for the first time you'll be able to reach the heart of the people. Their feelings!”
“We're looking for a girl named Bloom. We're old friends of hers.”
“Finally! We've captured the Last Earth Fairy!”
“It's the Universe Spirits; the circle has rejected her! This fairy, she's not the one we're looking for! There's nothing for us here, gentlemen. The hunt is still on!”