In science class, Ms. Hertz hands back tests and scolds Ulrich for his lack of effort, warning him about the possibility of being placed in remedial classes after an academic review that is being held the next day. At lunch, Jeremie tentatively announces to the others that he has found a way to virtualize them directly into Sector Five without the use of the Transport Orb. However, he suspects the procedure may be dangerous, and asks for a volunteer to test the program on. Ulrich, Aelita, Odd, and Yumi draw straws (or in this case, green beans) and Ulrich is chosen to be the "guinea pig".
That evening, the Lyoko Warriors meet in the Factory, and Odd, Aelita, and Yumi are sent to Sector Five via the Transport Orb. Ulrich is then virtualized using Jeremie's new program, but instead of arriving directly in Sector Five, he disappears completely. After manually devirtualizing the other three Warriors, Jeremie fails to locate him anywhere on Lyoko, and everyone, especially Yumi, becomes distraught. Later that night, Ulrich is somehow brought back to Earth in a scanner and quickly realizes he is invisible, inaudible, and incorporeal; a spectre-like ghost.
The next morning, Odd, Aelita, and Jeremie discuss Ulrich's disappearance in Jeremie's dorm. Ulrich arrives and discovers that no one except Kiwi can see or hear him. As Ulrich wonders what he and Kiwi can do to communicate with the group, the latter jumps out of Odd's arms and into Ulrich's ghost-like body, which leads to Ulrich unintentionally possessing the dog. After getting the group's attention by speaking through Kiwi, Jeremie deduces that Ulrich's inanimate body is somewhere on Lyoko, and is confident he can fix Ulrich by the afternoon. Ulrich then leaves Kiwi's body and possesses Jim instead, planning to argue against Ms. Hertz during the academic review and prevent himself from being placed in remedial classes.
Ulrich spends the morning as Jim and is bullied and harassed by students in the cafeteria. Then, he goes to the academic review with Odd (who has been class representative since the events of Lyoko Minus One and is thus required to attend as well), where he bickers with Ms. Hertz. Meanwhile, Jeremie calls Yumi and tells her that he has located Ulrich's body in Sector Five, but finds it is moving on its own and points out that it shouldn't be doing anything without Ulrich's mind. Yumi arrives at the Factory and is sent to Lyoko with Aelita to investigate.
Yumi and Aelita enter the Core Zone of Sector Five, where they traverse the large room without being crushed by piston-like booby traps. After Yumi touches the Key Mechanism and enters deeper into the Core Zone, she and Aelita discover Ulrich's avatar walking aimlessly and that it has been possessed by X.A.N.A.. He then uses Super Sprint to get away from them, prompting the two girls to chase after him and after a long run, X.A.N.A. opens a passage for Ulrich's body into the Great Hall, which is the chamber containing the Core of Lyoko. Jeremie cannot do the same, so he tells Aelita and Yumi to go into the Core Chamber by the South Pole Entrance.
Meanwhile, Ulrich, still in Jim's body, furiously defends himself against the other teachers, who want to place him in remedial classes. Ulrich succeeds in persuading every teacher but Ms. Hertz, who has lost faith in Ulrich and considers him a "lazy good-for-nothing." Desperate, Ulrich promises to teach her ballroom dancing, something she has been asking from Jim, if she gives him another chance, and she reluctantly agrees. Ulrich and Odd then excuse themselves from the academic review and set off for the Factory.
In the Great Hall, Ulrich's avatar attacks the Core with his new powers granted by X.A.N.A. while Yumi and Aelita battle several Mantas. The avatar succeeds in destroying one of the Core's two shield layers, and Aelita is devirtualized. Meanwhile, Ulrich and Odd arrive at the Factory. Odd is sent to Lyoko to help Yumi while Ulrich is told to leave Jim's body, causing the gym teacher to lose consciousness, and wait inside a scanner.
Yumi succeeds in defeating all but one of the Mantas before being devirtualized. Odd arrives at the Great Hall a short time later, defeats the last Manta, and engages Ulrich's avatar. After a short battle with possessed Ulrich's body and his clones, Odd devirtualizes the avatar, saving the Core and allowing Jeremie to merge Ulrich's incorporeal form with his body, returning him to normal.
The next day, Ulrich treats Jim with a new-found respect and spares him from Nicholas' prank. Later, when Jim is confronted by Ms. Hertz about the dance lessons, Jim claims not to remember, much to Ms. Hertz's frustration and disappointment.
- The original French name for this episode is Désincarnation, which translates to Disembodiment in English.
- The title card for this episode features the Holomap with only the Mountain Sector and Sector Five remaining; the Forest, Desert, and Ice Sectors were all destroyed in Lyoko Minus One, The Pretender, and Sabotage, respectively.
- This is the only episode to feature an energy beam being channeled through Ulrich's katana, which was a power that was temporarily given to him by X.A.N.A..
- The room in Sector Five that Aelita and Yumi traveled through in this episode before they deactivated the countdown was first discovered in Missing Link.
- This episode marks the second and final time in which an entity other than X.A.N.A. possesses someone; the first time was with Franz Hopper in Contact.
- The English version of this episode is notable for containing several scenes with poor dialogue syncing, all of which were fixed when this episode was uploaded on the Official YouTube Channel.
- It is also worth noting that on Netflix this episode also has the scenes with poor dialogue syncing.
- When Ulrich, in Jim's body, tries to calm the students down in the cafeteria, Aelita can briefly be seen sitting with Odd and Yumi. However, when Yumi receives a call from Jeremie a few seconds later, Aelita is shown to be in the lab with Jeremie.
|Code Lyoko: Season 3|
|Straight to Heart | Lyoko Minus One | Tidal Wave | False Lead | Aelita | The Pretender | The Secret | Temporary Insanity | Sabotage | Nobody in Particular | Triple Trouble | Double Trouble | Final Round|
|Season 1 · Season 2 · Season 3 · Season 4 · Evolution|