After a trip to Sector Five, Jeremie believes he has the data necessary to cure Aelita's virus. While Jeremie and Aelita work on the cure, Ulrich, Yumi, and Odd attend a rock-climbing contest in the gymnasium. It is seen that despite Ulrich's hesitation, Odd still convinces him to go to the gym.
The contest starts with Herb versus Odd; Odd is the winner. William later challenges Ulrich despite his obvious reluctance. Not wanting to be humiliated in front of his friends, especially Yumi, Ulrich accepts the challenge. Just as his friends push him to keep going, Ulrich gets dizzy and fall afterwards, which makes Yumi realize that he must have vertigo, a symptom that makes the patients feel the world or them-self is spinning. Ulrich runs away with embarrassment.
Meanwhile, Jeremie finds an anti-virus program and gives it to Aelita. Despite some problems with the application, it seems to work when Aelita remains safely. However, a bug in the program weakens her and ultimately causes her to turn invisible right after Jeremie announces the good news to Yumi and Odd.
Back to Ulrich's escape from the gymnasium, Yumi and Odd, thanks to Jeremie's tip, find him sitting and sulking in the woods. They try to cheer him up with the news from Jeremie, but the conversation is interrupted by a possessed pack of wolves, which are from X.A.N.A.'s latest attack. The three run away with horror and face a rock cliff. While Yumi and Odd climb up successfully, Ulrich, once again, faces his vertigo but still manages to reach the top thanks to Yumi. Sooner than expected, a wolf appears in front of their faces three seconds later. The wolf pushes Ulrich off and makes him fall. He then discovers that the wolves are just illusions and announces it to Odd and Yumi. However, after getting rid of the illusions, they realize that three of the wolves are indeed real animals.
After they receive a phone call from Yumi, Aelita insists that Jeremie virtualizes her to the Ice Sector to deactivate the tower in the ice cave. When she arrives, it turns out that the mentioned error in the anti-virus program blocks Aelita from entering any tower on Lyoko as the towers do not recognize her, resulting in her inability to prevent X.A.N.A.'s attack. Then the Scyphozoa arrives to capture Aelita but she immediately freezes the creature with ease in the ice block and tries to leave the cave.
After hearing Jeremie's request for Aelita's aid, Ulrich orders Yumi and Odd to help Aelita while he fights the wolves by himself. After tries kicking them with a stick, Ulrich runs toward the city to seek for help. He contacts Jeremie and gets a sudden attack from the back by a wolf, which is seen by Jeremie through his computer screens.
Meanwhile, Yumi and Odd are transferred to Lyoko and look for Aelita, but are blocked by a Megatank. Yumi gets devirtualized while Odd manages to defeat the monster. Aelita, on her way to the exit, encounters two Hornets and runs back to the cave. Accidentally, she returns to the spot where she froze the Scyphozoa. The creature unleashes itself in front of a horrified Aelita, and the Hornets reach her from the back. While Aelita is literally hung up, Odd manages to reach her spot and sneaks past the Hornets by swimming underwater. He frees Aelita from the Scyphozoa by using his Laser Arrows.
Jeremie, still working on deleting the anti-virus program with Yumi along his side, and both of them witness Ulrich collapsing inside the factory. Yumi attempts to help Ulrich, but the anti-virus program is stopped and deleted at the same time, so Jeremie stops her. Eventually, Aelita enters and deactivates the tower and Jeremie launches a return to the past to heal Ulrich's injuries and send the wolves back to where they came from.
Back to the day earlier, while William mocks Ulrich for being dizzy, Ulrich gets revenge by announcing William's fear of spiders (which he discovered from Sissi) and calls him Spider-Man before leaving with his friends, all while Odd compares Aelita's invisibility to Sue from the Fantastic Four.
- The original French name for this episode is Vertige.
- Chronologically, this episode takes place after the events of both Temptation and A Bad Turn. However, it aired before either.
- At the beginning of the episode when the group is in Sector Five, it is revealed that Mantas can deploy flying mines.
- It is also revealed that William is afraid of spiders.
- The tower activated in this episode might be the same tower X.A.N.A. activated in Satellite.
- At the beginning of this episode when Jeremie is trying to find to key the timer shows a minute and eight seconds but when the key is activated by Odd the timer shows a minute and sixteen seconds.
- When Jeremie tries to call Yumi in the sewers, she says "Konnichiwa" in her cell phone's voicemail message when she would have actually said "Moshi moshi" in the Japanese language. The Japanese use that phrase to answer the phone.
- The sweater which Aelita wears as her sporting clothes is gray instead of a dark pink.
|Code Lyoko: Season 2|
|New Order | Uncharted Territory | Exploration | A Great Day | Mister Pück | Saint Valentine's Day | Final Mix | Missing Link | The Chips Are Down | Marabounta | Common Interest | Temptation | A Bad Turn | Attack of the Zombies | Ultimatum | A Fine Mess | X.A.N.A.'s Kiss | Vertigo | Cold War | Déjà Vu | Tip-Top Shape | Is Anybody Out There? | Franz Hopper | Contact | Revelation | The Key|
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