The episode begins with Jeremie in the process of reprogramming the MegaPod. Then, Aelita enters his room and asks about his progress on the program because she eagerly wants to return to the Cortex to find out more about why a picture of her father was in there. During the course of this conversation, the final calculations are completed, and Jeremie tells Aelita that they can go back to the Cortex as soon as possible, after class of course.
The scene then shifts to Yumi telling Ulrich, Odd, and William about her concerns relating to her cousin back in Japan who, due to the recent earthquake and catastrophe, has lost pretty much everything including the school. Ulrich remarks that he knows how to deal with a X.A.N.A. attack and that storms aren't really his thing. Yumi scolds him by saying that everything isn't about the virtual world, that the real world needs their help too. Odd then begins to throw out an idea, but Jeremie and Aelita arrive and tell the rest of the group the great news about the Megapod. Yumi still is apprehensive about going to Lyoko because she wants to help Japan somehow, and then William points out that the Megapod only has four seats; so everyone isn't required to go. Jeremie agrees that everyone doesn't have to be there today, and Yumi thanks everyone for letting her have some free time to do what she wants. Ulrich appears to be slightly distressed, either that Yumi's not coming or that William came up with the idea in the first place.
Everyone except for Yumi then proceeds to the factory for the next mission, and along the way Odd asks Jeremie what modifications he has made to the Megapod. Jeremie says that he has improved a lot in the navigation and handling systems and that he also added power to the engines if a turbo is required in the future. William asks about if they are attacked while inside, and Jeremie replies that he added a firing sequence. William is impressed and compliments Jeremie. Aelita reminds everyone to focus on the mechanics later and instead on the mission at hand.
The scene then shifts back to Yumi in Mr. Delmas's office asking him about her plan to throw a party for a fundraiser to help with rebuilding her cousin's school. Mr. Delmas thinks it's a great plan and then looks into his schedule to see when the gym is next available, but unfortunately it appears that the only time the party can be thrown is that same night to Yumi's distress. Yumi takes his offer anyway and then goes off to prepare.
Back in the factory, everyone is going to his/her stations. William politely lets Aelita take the scanner before him, which makes Ulrich quietly remark to Odd about William being a showoff. Jeremie lets the team know about a virtual card key of sorts he created that needs to be used in the Cortex so that he can analyze any data they find there. The warriors virtualize in the Carthage arena section, during which William ends up almost landing on Ulrich. Ulrich gets mad about it, but Aelita refocuses the two and they all head to the Skid to take a trip to the Cortex. On the way to the hangar, Odd tries to quietly remark to Ulrich and William that Aelita seems more stressed than usual, but Aelita overhears him and gives Odd a cold stare. They begin the journey to the Cortex.
Yumi, meanwhile, is starting the long process of setting up the party back at the gym; and Jim is helping her bring materials inside. Jim tells Yumi that this reminds him of the days when he was in charge of the Rolling Strook's tour, but when Yumi inquires about those days Jim says that he'd rather not talk about it. Jim then leaves, and Yumi then realizes the daunting task of setting up the party all by herself.
After they arrive in there, Jeremie virtualizes the MegaPod and the group argues about who gets to drive it next. Ulrich prefers that Odd doesn't drive it, William thinks it should be him, and Odd thinks he should. Aelita and Jeremie however vote for Odd to drive it due to his skill in video gaming (Odd apparently has the current high score in Galactic Destructor). Jeremie reminds him to beware of the trap in the Cortex. When the floors and walls are open, Odd drives too fast and almost hits one of the walls. Eventually, after many close encounters with the danger of devirtualization, they arrive at the core. Odd cheekily asks everyone how he did, and William calls Odd a psycho. Odd tells him that he can "take the bus" next time.
Back at Kadic, Yumi is trying to find some people to help her set up the party; but it seems that everyone is booked tonight and can't help out. Yumi seems to have asked everyone, but then a boy comes up to her and asks if she needs help. She doesn't recognize him, but he says his name is Remi and that they share a class together. Yumi takes his offer to help out and is glad that she is not alone in setting the party up anymore.
On Cortex, the group arrives at the door of the core of Cortex, and they wonder how to get it open. Aelita said that last time it opened due to a shock of sorts. Aelita uses her abilities to open the gate, and everyone is surprised that she was able to do so. Aelita begins to wonder if her father had created this door, and William steps in and reassures her that if she did see a photo of her father in here before, then they can't just sit outside; the answers to all of her questions are inside.
In the gym, Remi ends up breaking the sound system, and Yumi realizes that having Remi as help is not the best help she could've gotten.
Inside the core, the team enters and everyone (except Aelita, for she has already been inside here before) is amazed by the sights they see. Aelita spots the terminal again, but before she rushes down there, Ulrich tries to calm her doubts about her father. He says that her father is a good guy, and Odd chimes in and reminds her that her father had sacrificed himself to defeat X.A.N.A. back in the day. Jeremie agrees with them both and assures her that the data he'll get will confirm that her father has nothing to do with X.A.N.A.'s return. Jeremie then virtualizes the key cards he had talked about before, and Aelita races to the terminal. However, there is a trap and Ulrich and Odd are devirtualized by the walls of the core crushing down upon them. William saves Aelita and gets devirtualized soon after, leaving Aelita alone. She manages to get to the terminal and put Jeremie's device in; the download begins to take place. Odd compliment William's actions in the core, which frustrates Ulrich slightly. Ulrich gets a call from Yumi asking for his help, and Ulrich tells her that he'll be there. Odd and William tag along with him. Yumi thanks them for coming and then starts to tell them where they can help out the most.
Back in Sector 5, Aelita gets word from Jeremie that the information from the Cortex's supercomputer he had recieved from the terminal is the exact kind of coding her father had programmed into the supercomputer at the factory. She can't belive the news that she's hearing and tries to figure out why her father would be connected to that data at all. Jeremie apologizes for upsetting her and tells her that he will continue searching the data and that she can take as much time as she needs before coming back to the real world.
Back at the gym, Yumi seems to be overly stressed at how slow everyone seems to be moving. She goes over to Ulrich and asks if he's fixed the sound system yet, but Ulrich remarks that it is completely busted and that it's not an easy job. Yumi snaps back that it looked like he hadn't put much effort at all into fixing it, and Ulrich snaps back that he would fix it if she would give him enough time and to give him a little slack. Yumi says that he might be the best on Lyoko but that on the real world he's useless, and Ulrich says that he misses the Lyoko-Yumi instead of the real world one because the real-world one is a control freak who barks orders. Ulrich then storms off, but William, who has been listening in on the fight the entire time, follows Ulrich.
On Lyoko, Aelita walks to the edge of a walkway in Sector 5 and tries to communicate with her father to answer her questions about his possible responsibility in X.A.N.A. return.
William follows Ulrich outside and tells him that Yumi really needs his help. Ulrich asks why he should, to which William responds that Yumi won't be able to make it through without his help. Ulrich, believing that William has other motives for telling him this, accuses him of doing this because he still has a crush on her and asks why he's doing this in the first place. William simply responds by saying that he's tired of being seen as the bad guy and that everyone deserves a second chance.
Inside the gym, Odd is unsuccessful at fixing the soundboard and Yumi says that she'll have to cancel the party. Ulrich and William return, and Yumi is pleased that they came back and apologizes for her behavior earlier. Odd informs the group that they're in danger because Remi (who is standing close to an outlet) has three Spectre clones of himself now. Jeremie calls Odd to let them know about the attack, and Odd informs him that they already know. Facing no resistance or obstacles from X.A.N.A. at all, Aelita goes to the Desert Sector and makes her way to the tower. Odd points out to the rest of the group that there's only one way to get out of the gym and that it's behind the row of spectres. Ironically, one spectre fires a bolt of electricity and fixes the broken sound system, and classical music starts playing. Aelita makes her way up the tower while Ulrich and William decide that they as a group show charge the spectres. Before reaching the spectres though, the spectres vanish due to Aelita's deactivation of the tower. They check on Remi, who has no idea what happened. Yumi then tells the rest of the gang about the jobs left to complete, and everyone is eager to help out, to her delight.
Aelita still remains on Lyoko, and Jeremie asks her where she's heading to. Aelita tells him that she just needs to feel Lyoko. She then says that Lyoko is just like her father, and Jeremie asks what she means by that. Aelita explains that Lyoko is peaceful and serene like her father, unlike the Cortex which is chaotic and unstable, like X.A.N.A. She's also determined in her heart that her father had nothing to do with X.A.N.A. returning, even though the data coming from the Cortex seems to state otherwise. Jeremie agrees with her, and promises to investigate the data thoroughly to prove that her father did not bring X.A.N.A. back.
- The original French name for this episode is Soupçons.
- Aelita starts to investigate why a photograph about her father that appeared in the Cortex.
- First episode that Odd drives the Megapod.
- This is the first episode in the fifth season that Aelita uses her Creativity ability.
- William rides in a Nav Skid and the Megapod for the first time.
- First episode that William is devirtualized normally without X.A.N.A. controlling him.
- This is the first episode in the fifth season that Jim makes an "I'd rather not talk about it" remark.
- Mr. Delmas makes his first appearance in season 5.
- William goes into the Skid for the first time
- Jim stated that he once organized a Rolling Stones concert.