After going through all of Franz Hopper's diary, Jeremie discovers the truth behind the supercomputer, at least to some extent. Hopper had used it quite extensively, to the point of repeating a single day for more than seven years. His sanity degraded throughout the experience. Hopper also revealed that he and Aelita hold the Keys to Lyoko, which were what XANA was after. He only needed her half, now. The Keys would allow him to escape the supercomputer. Jeremie also finds a way to free Aelita from the supercomputer.
It turns out that Aelita never had a virus. In fact, XANA had been holding onto a piece of her, which was responsible for linking her to the supercomputer. Aelita is not willing to go, angry over the fact that Hopper had essentially taken her life from her. She's also worried that XANA might escape. To that end, she shuts down the supercomputer. Jeremie rescues her, and the group goes to Lyoko to retrieve her fragment. After all their efforts, they seem to succeed, but it turns out to be a fake. XANA manages to devirtualize Aelita's defenders and steal her memory, effectively killing her and allowing him to escape, which shuts down Lyoko in the process. His escape allows Franz Hopper to revive Aelita and Lyoko, restoring all of Aelita's memories in the process. Through the restoration, Aelita finally remembers her past up to the point that she went to Lyoko. With XANA now free and Aelita's memories returned, neither are linked to the supercomputer. This means that they could shut it down, but it would do no good. Unsure of how they'll proceed, Jeremie promises that they'll find a way to stop XANA.
This episode contains examples of:
- Anger Born of Worry: Jeremie has this in response to Aelita committing suicide.
- Apocalyptic Log: Franz Hopper's diary.
- Art Shift: Aelita's memories are initially drawn with softer colors and lines and freeze frames, until the point when The Men in Black raid her house, at which point the art style switches to the show's usual style but in sepia tone.
- The Bad Guy Wins XANA succeeds in stealing the Keys to Lyoko and escaping the supercomputer.
- Badass Boast: Jeremie, in response to XANA stealing the Keys to Lyoko and escaping the supercomputer, regarding their next steps.Jeremie: Same as always: We fight! XANA may have become more powerful, but I don't think he's invincible. If he attacks, we'll counterattack! We'll find a way to defeat XANA for good.
- Being Watched: Franz Hopper feels this way in the recordings. He turns out to be Properly Paranoid, as The Men in Black do eventually come after him.
- Big "NO!": Jeremie yells this when Aelita's memory is being taken away.
- Bland-Name Product: One of the posters in Aelita's room appears to takes cues from Hello Kitty.
- Blunt "Yes": Ulrich is quick to agree to Sissi's invitation of going to the dance with her. This actually surprises Sissi, who is left at a loss for words for a moment.
- The Cameo: Kiwi is seen near the end of the episode, where Aelita pets him until she doesn't want to anymore.
- Collapsing Lair: The room with Aelita's fragment starts collapsing as Ulrich and Aelita approach the fragment, though Franz Hopper's controlled Mantas help Aelita reach the fragment. Once Aelita reaches the fragment and grabs it, revealing it to be a trap, the room starts collapsing again, with Ulrich and the Mantas crushed by the platforms leaving Aelita with no way to escape.
- Driven to Suicide: Aelita, despairing over the fact her father took her life away from her, shuts down the Supercomputer in an attempt to Save the World, which almost results in her death. Fortunately, Jeremie finds her and turns it back on.
- Empathic Environment: When Aelita temporarily dies, Lyoko briefly darkens and the towers turn red. On Earth, XANA's escape from the supercomputer causes a storm over the Factory.
- Forced to Watch: Yumi, Ulrich, Odd, and Jeremie all watch helplessly as XANA steals Aelita's memory, killing her.
- "Groundhog Day" Loop: An invoked variant on the part of Franz. Franz Hopper deliberately repeated the same day 2,546 times (almost 7 years) using the return to the past feature, to completely develop the supercomputer, Lyoko and XANA. This is shown to have taken a toll on his sanity, making him incredibly paranoid (which was justified due to The Men in Black tracking him.)
- Heroic Sacrifice: Franz sacrifices himself to save Aelita and give her back her lost memories, as well as keeping Lyoko alive. His fate afterwards is unknown.
- High-School Dance: Middle-school dance, as the case may be. The end-of-the-school-year dance is approaching. Although the dance causes some drama between Ulrich and Yumi, and Odd searches endlessly for a date to the dance, the heroes end up never actually attending as they go to the factory to find Aelita's missing fragment instead.
- Hope Spot: Things look bleak as the heroes reach the room with Aelita's fragment, as Odd and Yumi are both defeated by Creepers, and then, the room starts falling apart, with Ulrich and Aelita about to fall into the depths, until Mantas controlled by Franz Hopper fly in save them. The Mantas allow Aelita to reach her missing fragment and collect it, but it's revealed to be a trap, with the entire room starting to fall apart again, crushing Ulrich and the Mantas, leaving Aelita completely alone at XANA's mercy.
- I Did What I Had to Do: Aelita uses this justification as to why she turns off the super computer, and temporarily killing herself and XANA.
- Kidanova: Odd's two-timing tendencies are finally catching up to him. Most girls he has been involved with don't want anything to do with him, and his reputation makes other girls unwilling to date him.
- Missing Mom: It's not clear what happened to Aelita's mother, just that she disappeared one day. It's up in the air if The Men in Black killed her, or ran away. Either way, the episode does not provide any answers.
- Moment Killer:
- Yumi is about to ask Ulrich to go to the school dance with her, when William shows up, interrupting them and dragging Yumi away. This causes Ulrich to think that Yumi wants to go to the dance with William.
- Later on, Ulrich goes to Yumi's house to apologize for getting upset at her for his mistaken assumption. He then says that he has to "tell her something", and they have a Held Gaze and romantic music plays in the background. But, their conversation is cut short when Jeremie calls to summon them to the factory.
- Pyrrhic Victory: XANA has escaped the supercomputer, but Franz manages to revive Lyoko by sacrificing himself so that Aelita and Lyoko could live, and also restores the missing piece of Aelita, so she is now free from the supercomputer too. The drawback is that the supercomputer is now completely useless for shutting down XANA.
- "Ray of Hope" Ending: Aelita has more freedom from Lyoko, but XANA now has a specific goal, to absorb her memories using the Scyphozoa. In the last episode of the season, he succeeds and manages to escape Lyoko, no longer relying on it and becoming far more powerful than before. However, when the heroes seem out of ideas, they get a message from the enigmatic Franz Hopper, pledging his help.
- Sanity Slippage: Franz Hopper, in the video diary, is shown experiencing this to an extent, getting paranoid that someone wants to get rid of him. That he repeated the same day for almost 7 years presumably contributed to his paranoia; however, it turns out to be Justified, since The Men in Black are coming after him at this point and he fears for Aelita's safety.
- Scary Shiny Glasses: Averted in that Franz wears these glasses constantly, and happen to make him eviler than he really is.
- "Shaggy Dog" Story: The season-long quest to create an anti-virus for Aelita essentially ends as this, given The Reveal that Aelita never even had a virus to begin with, and her link to XANA was caused by something else that gets resolved by the end of this episode.
- Smoking Barrel Blowout: Odd engages in one after getting rid of a Creeper, blowing on his finger and "holstering" it on his side.
- The Reveal: Aelita never had a virus, XANA had instead taken a fragment of her, which is what linked her to Lyoko.
- Unexpectedly Dark Episode: For the series as a whole, this is a very dark episode, dealing with Aelita attempting suicide in order to save the world from XANA, her mother disappearing, her and her father running away from home to evade who are likely government authorities. On top of these themes, The Bad Guy Wins and succeeds in killing Aelita while in Sector 5, at least briefly.
- Weather Manipulation: XANA does this when Sector 5 shuts down and is freed from the supercomputer, turning the area around the factory into a big storm.
- Wham Episode: In addition to revealing the real reason that he was able to link Aelita to Lyoko, the episode ends with XANA outright winning against the heroes and escaping into the internet.
- Wham Shot: Multiple examples in rapid succession.
- The Scyphozoa suddenly appearing in Sector Five to capture Aelita and drain her memories... after all of the other Lyoko Warriors have already been devirtualized.
- Several seconds later, Aelita's life points hit zero and she falls to the ground lifeless, with Jeremie outright confirming she's dead.
- Sector Five goes dark as every tower on Lyoko is activated at the same time.
- Finally, the scene cuts outside, where a massive storm has formed as XANA escapes into the internet.
- You Are Not Alone: Aelita says "Fighting XANA is my job" in such a way that makes one think she has to do this alone. However, Jeremie and the others join hands, and he says, "No, Aelita, it's our job."
- You're Insane!: Yelled by Jeremie to Aelita when she shuts down the Supercomputer, temporarily killing herself.Jeremie: You're insane! Why would you do that?!
