The episode opens the morning before a Subdigitals concert. Aelita, who had won a contest to be the band's opening act, is harassed throughout the day by fans and critics alike; even Milly and Tamiya want an interview with her to the Kadic News and have been bothering her all week. Aelita reveals to her friends that she is nervous and scared of performing in front of a large audience as playing for a school party or all alone is a totally different thing. She decides to turn to Jeremie for support, but is stopped by Nicholas and Herb who ask her for her autograph. She becomes very embarrased by this and Sissi scolds the pair for asking Aelita for the autograph and mocks her that she will soon make a fool of herself and become a laughingstock during the concert. After the trio walks away, Aelita enters Jeremie's room, who says that everything will be just fine and Odd, Ulrich, and Yumi will be there to give her support. But when Aelita questions his attendance, he reveals that he is engrossed in searching for new Replikas and is not willing to stop working to attend her concert. Hurt, Aelita lashes out at him and cries. She decides to go to the rec room to give Odd, Ulrich, and Yumi their tickets. There, Yumi immediately notices there is something wrong with Aelita and Odd points out that it must have been Jeremie who managed to upset her, to which Aelita confirms his assumptions.
That night, a large crowd gathers at the concert venue, and Aelita prepares in her dressing room. Yumi, Odd and Ulrich decide to pay her a visit in her dressing room to cheer her up and Yumi points out that she looks gorgeous and will steal everyone's hearts during the performance. It turns out that Jeremie remains in his dorm room working on his computer until Yumi calls him just before the concert starts and berates him for breaking Aelita's heart by not appearing. He apologizes for that and promises to be there as soon as possible. Just before Jeremie can even get ready to leave, however, the Superscan detects an activated tower in Lyoko's Mountain Sector, and X.A.N.A. sends a spectre to the concert. Backstage, Sophie, the Subdigitals' manager, is possessed by the spectre and attacks Aelita in her dressing room. Sophie then instructs the Subdigitals to go on without Aelita as their opening act. Yumi, Odd, and Ulrich are confused by Aelita's absence until Jeremie calls them to inform them of the X.A.N.A. attack.
As Jeremie arrives at the Factory, Ulrich, Odd, and Yumi force their way backstage to find Sophie leaving the building with an unconscious Aelita. However, before the trio can pursue her, they are intercepted by Milly and Tamiya, who are revealed to be possessed as well. Ulrich volunteers to fend the girls off while Yumi and Odd escape. Yumi then calls Jeremie and informs him of the kidnapping, correctly deducing that Sophie is taking Aelita to the Factory. Jeremie waits on the main floor of the Factory to intercept Sophie, but the superpowered woman quickly knocks him senseless before going down to the scanner room and virtualizing Aelita, still unconscious, onto Lyoko's Mountain Sector.
Aelita quickly regains consciousness as Odd and Yumi arrive at the Factory to find Sophie in the Lab. The two work together to incapacitate the woman while Aelita fends off several monsters. However, when William arrives, Aelita is forced to flee. Jeremie then enters the Lab, having recovered from his fight with Sophie, and sends Yumi and Odd to Lyoko, where an aerial battle quickly ensues. As Ulrich continues to fend off Milly and Tamiya backstage, Yumi, Odd, and William dogfight using the Overwing, the Overboard, and the Black Manta, respectively.
As Aelita continues to battle monsters on her way to the activated tower, Sophie regains consciousness in the lab and attacks Jeremie. After taking control of the interface, Sophie dematerializes Yumi and Odd's vehicles, putting them at a disadvantage before assaulting Jeremie once again. Odd and Yumi work together to perform an attack and Yumi then sacrifices herself to defeat William, and both are devirtualized. Odd then takes control of William's Black Manta and comes to Aelita's aid and defeats the Manta that was attacking her, allowing her to deactivate the tower, saving Jeremie from Sophie and saving Ulrich from Milly and Tamiya. Jeremie then launches a return to the past, bringing them back to before the concert.
In Aelita's dressing room, Jeremie arrives and wishes Aelita luck. Aelita then apologizes for lashing out at him earlier that day, and Jeremie apologizes for missing the concert the first time saying he could not miss it for a second time. Then, once the concert starts, Aelita comes out on stage and performs well, having seemingly beaten her stage fright and everyone is having a great time while listening to her music.
- The original French name for this episode is Il est sensé d'être insensé, which translates loosely to It's Sane to Be Insane in English; this is a reference to a line Jeremie says to Aelita at the end of the episode.
- This is the only episode in which Alain le Dong, a regular storyboard artist for the series, is credited as a writer.
- The songs Planet Net and Break Away are performed by the Subdigitals in this episode.
- In one scene when Aelita tries to run towards the activated tower and the Manta starts shooting at her, the mountains in the background disappear.
- Whenever the scenes involving Yumi and Odd fighting with William on the big plateau are shown, the activated tower on the section where Aelita is, disappears and the platform with the mountain next to it suddenly appears.
The original episode summary can be found here.