Sometime into the new school year, a twelve-year-old boy-genius named Jeremie Belpois stumbles upon an abandoned factory while looking for potential parts for his miniature robots. In his search, he finds the lab and decides to reactivate the supercomputer to see what is on it. When he turns the monitors on, he accidentally awakens a mysterious, pink-haired Artificial Intelligence who immediately asks where she is.
The next morning, a new kid at Kadic Academy introduces himself to Ulrich Stern as "Odd Della Robbia, your brand new roommate." Ulrich draws the line right then and there, telling Odd to take things nice and slow between them. At this point, Sissi Delmas arrives to tell her "Ulrich sweetheart" to meet her at her dorm at eight that night. Odd takes an immediate interest in Sissi, despite Ulrich's claim that she is a "brain-dead leech". Odd continues to pester Ulrich after class with lame jokes, claiming that "by the end of the day, Ulrich won't be able to do without him".
During a morning break between classes, Jeremie returns to the lab to make contact with the mysterious A.I. he met last night, dubbing her "Maya". While he's able to answer her question of where she is; a virtual world called Lyoko, he doesn't know why she's there. When Maya steps out of the way tower she'd woken up in, she discovers a large forest and shows Jeremie a visual of it. While Jeremie looks further into this development and finds three other sectors with different environments, Maya is approached by two cockroach-like creatures, who begin firing at her. She rushes back to the tower, where Jeremie notices that her life points are regenerating.
As Ulrich is checking out a Japanese girl, who is purchasing a drink from the vending machine, Odd continues to pester him about Sissi. Ulrich tells Odd that he's "not her type". As Odd counters, Jeremie attempts to make a selection on the vending machine and is promptly electrocuted. A mysterious logo identical to one that was on the Lyoko monsters appears unnoticed on the machine's buttons. Ulrich takes Jeremie to the school nurse, while Odd tells the teacher.
As Jeremie heals, Ulrich attends a martial arts class that consists only of him and listens as Jim Morales, the instructor for the class, makes a joke comparing names of various martial arts to dishes at a Chinese restaurant. The Japanese girl seen earlier shows up to attend the class as well as he does and he quickly apologizes for any offense he may have inflicted, revealing her name to be Yumi Ishiyama. She easily brushes it off, stating that she is Japanese. When mentioning it in passing and urged further by his students, Jim tells his students of a time he was attacked by a beaver while working as a forest ranger in Quebec; the tale sends the kids into a fit of laughter, and they tell Jim they would've been better off not talking about it (which caused Jim to say this often later on in the series). After the joke dies away, Ulrich and Yumi begin sparring, a session that ends with her defeating and pinning Ulrich to the ground. As they continue to briefly spar, they pause and blush at each other. Once this awkward moment passes, Jim ends the session and Ulrich leaves without returning Yumi's bow, an act she mildly resents.
When Ulrich returns to his dorm, he finds all of his things trashed because of Odd's dog, Kiwi - whose presence at the academy is a violation of school rules. Angry about the mess, Ulrich threatens to tell the principal about Kiwi and leaves. As this happens, Jeremie continues to work in his own dorm when his screen blacks out then displays the same strange logo that was on the Lyoko monsters and the vending machine. Ulrich hears Jeremie's screams and runs to his dorm, only to discover Jeremie being attacked by his miniature robots. After rescuing him, Ulrich demands to know what is happening. After some persuasion, Jeremie gives in on the condition that Ulrich keeps what he's about to learn a secret.
After Jeremie takes Ulrich to the factory (during an incident leading Jeremie to believe Ulrich is afraid of heights, which he quickly denies), he introduces him to Maya and gives him a recap on everything that has happened regarding Lyoko. He also points out that his computer screen, at the time his robots attacked, had a logo on it identical to the one on the monsters that attacked Maya. Concerned about the danger the computer seems to pose, Ulrich suggests Jeremie shut it down and call the police. Jeremie agrees, but only on the condition that he materializes Maya onto Earth first, claiming he found something that could make this possible.
This leads them to the floor below, where Jeremie shows off the scanner room. Ulrich doesn't believe Jeremie when he tries explaining what the scanners do, so Jeremie suggests the use of a guinea pig to test it. Ulrich quickly nominates his roommate's mutt and returns to the dorms to fetch him. However, he is quickly followed by Sissi, who was still waiting for Ulrich to meet her, and Odd, alerted to his presence and the theft of Kiwi. The two find the factory just as Ulrich places Kiwi in an open scanner and climbs up to the lab to tell Jeremie to start the procedure. Unfortunately, Odd picks up Kiwi who then jumps out of scanner, leaving his master to be virtualized.
Odd finds himself in the Forest Sector dressed, to his bemusement, like a large purple cat. He finds the video game feel to the place cool until the same monsters that attacked Maya ambush him, and Ulrich suggests having Sissi and himself virtualized to help him. Sissi backs out, however, so Ulrich goes alone, appearing on Lyoko as a samurai. Given that their forms are created without programming them, Jeremie assumes that their forms are based on their subconscious thoughts. Odd remains envious of Ulrich's katana until he discovers he can fire arrowheads from his wrist, of which after he says, "I take those words back!" after complaining that he does not have a cool weapon.
While Sissi and Kiwi find their way to the lab where Jeremie is, he attempts to guide Ulrich and Odd to Maya's tower. Jeremie's attempts are interrupted when the three in the lab are attacked; the wires on the floor are suddenly coming to life. Left on their own, the two boys on Lyoko accidentally stumble though one of the towers and find themselves in an icy landscape. Ulrich points out that one of the towers is glowing red instead of blue like every other tower they've seen. The two are soon ambushed by a group of block-like beings that soon devirtualize them out of Lyoko, but not before Ulrich manages to destroy one of them.
Now back in the real world, Ulrich and Odd race to the lab to save Jeremie, Sissi, and Kiwi from their attackers. Ulrich's rescue attempt fails at first, but Odd soon steps in to save his roommate, reminding him of his claim that morning that he wouldn't be able to do without him. After the attack subsides, Jeremie contacts Maya and informs her that they're okay. Meanwhile, back in the Ice Sector of Lyoko, the tower Ulrich spotted earlier still glows red.
- The original French name for Part 1 is Le réveil de X.A.N.A. partie 1.
- Jeremie's name for Aelita, Maya, is the name of an animation program.
- This episode shows that the first sector Odd and Ulrich were virtualized in was the Forest Sector.
- In this episode, Ulrich is shown using Super Sprint for the first time, but does not use his special abilities of Triplicate or Triangulate.
- Odd is shown using is shield for the first time in this episode. He did not use his psychic ability of Anticipation.
- Since by the time this episode aired, the Lyoko models of the characters had been improved/updated, it doesn't make much sense that Aelita has her lure-like earring located at the bottom of her ear when in Teddygodzilla (which chronologically happens after this episode) and the entirety of Season 1 she still had it located higher in her ear.