The episode begins as our heroes are fighting in the Ice Barrier Sector. They are trying to get Aelita to a Tower after an attack not shown in the episode, and are being attacked by numerous Blocks. They defeat them, then return to the past to shut up Odd, who had made a very dry and unhilarious joke ("Hey, Jérémie. Next time just enjoy the show and let the real pros get the job done, okay?"). Unknown to the three, XANA has locked them up inside a parallel world.
The next few days at school, Jérémie notices that Odd, Ulrich, and Yumi are not in any of their classes, neither are they in their rooms, much to Mrs. Hertz's motherly worry of the three.
Jérémie, feeling panicked that he has lost his friends (he states that something must have gone wrong in the return trip), asks Aelita if they're still on Lyoko, but she tells him they're not. To make matters worse, Jim catches him (having snuck into Jérémie's room), and takes him to Mr. Delmas's office. The Principal asks Jérémie where the others are. Jérémie tells him he doesn't know, then takes a 3-minute break, during which he asks Aelita for help.
Aelita tells him she can hack into the school's computer systems just like XANA. Jérémie then takes the principal and Jim to the Boiler Room, where, under Aelita's command, the pipes explode and Jérémie escapes to the Factory.
By this time, Aelita has an idea of what has happened to the others. She shows him a sound byte she recorded of the parallel world (according to her, a sort of radio or TV station transmission). She warns him to be careful in watching it, as it is very weird. In it, Ulrich and Odd are doing aerobics, stretching, and push-ups with Jim. Suddenly, Nicholas hits Herb, who then proceeds to yell at his friend. Suddenly, the two fizzle, rewind, and Nicholas does the same thing. Yumi goes over to Jérémie, who is sitting on the bleachers, immersed with his laptop. She tells him of the weird goings-on, and Jérémie informs her he is having difficulty contacting Aelita. She then asks the seemingly real Jérémie why he isn't doing physical education, and he replies that Jim agreed to excuse him. Jim then waves at the two from the track, and Yumi comments that it is incredible.
The real Jérémie then realizes that XANA has captured them and valiantly says he will rescue his friends, clearly showing his courage. He then says that if he does go into a virtual world, he would much rather do it to find Aelita waiting there for her quasi-boyfriend.
Aelita remotely operates the scanner to virtualize Jérémie. He virtualizes inside the fake Kadic, which is inside a giant orange energy bubble that resembles a Guardian. XANA, in the form of the virtual Jérémie, is at the computer in his room, and notices that Jérémie has arrived (his comments seem to suggest that he had been waiting for Jérémie), and dispatches zombie-like versions of Herb, Nicholas, and Jim to get him. Jérémie escapes them after a long chase, and heads for the fake Factory.
Once there, he finds that his friends are about to be lured into fake Scanners by XANA, who will then kill them by deletion once and for all. Team Lyoko at first can't decide which Jérémie is the real one, but eventually pick their friend after an argument between the two Jérémies. At this, XANA gets enraged and teleports the zombie Jim, Herb, and Nicholas in to kill Odd, Ulrich, and Yumi, whilst he tries to crush Jérémie with cables summoned from the floor. Only Aelita's creativity saves the day, when she breaks the bubble with her beautiful song. As the fake world breaks down, Jérémie is ejected from the world and is devirtualised. Odd, Ulrich, and Yumi escape to find out they remember nothing of the ordeal, but are distracted by a horde of Blocks, whom they happily fight.
This episode contain examples of:
- Big "NO!": During their attack by XANA in the fake world, Jérémie lets out a big one, thinking that everyone will be gone and Aelita will be left alone. When the attack is over, Yumi lets out one as Jérémie is suddenly yanked out of the fake world and thrust back into the real world again.
- Bolivian Army Ending: Zigzagged. The episode ends with the heroes rushing to fight a large army of Bloks, and while it's pretty obvious that they made it through, the viewers don't see it.
- Epiphanic Prison: What the fake Kadic is; Yumi, Odd, and Ulrich don't even realize they're trapped until Yumi starts getting suspicious.
- Evil Cannot Comprehend Good: The flaw in Xana's plan; he accuses Jérémie of lying, as Jérémie is usually too scared to virtualize himself. Clearly, the concept of loyalty and friendship confuses him, and he's wrong anyway as Jérémie had virtualized himself prior to this episode of his own free will in an attempt to talk to Aelita in "Frontier" to clear up an argument they both had.
- A Glitch in the Matrix: Odd, Ulrich and Yumi notice inconsistencies in the world XANA has trapped them in: the people around them repeat the same actions and sentences unnaturally as if not actually present. This is explained as XANA lacking a full understanding of how humans act, only having "estimates" and mere theories.
- Guile Hero: Jérémie is no different on Lyoko than he is on Earth, and has to use his smarts and his wits to solve the problem.
- Faceplant: Jérémie ends up faceplanting into the alternate dimension. Considering he's never (successfully) gone to Lyoko before now, it's understandable.
- He Who Must Not Be Seen: For once, averted with XANA, who appears in the form of virtual Jérémie.
- "Just Joking" Justification: Odd's boneheaded antics nearly get him devirtualized, but he pulls off a spectacular return, earning him praise from his teammates. He then proceeds to tell Jérémie to sit back and let the "real heroes" take care of things. He starts laughing but then realizes the rest of the team are giving him a Death Glare. He protests that he was just joking but it quickly becomes apparent the claim is falling flat. Even though the real Jérémie is able to blow off the comment, XANA exploits the moment for his fake Jérémie to not talk to Odd.
- Logic Bomb: Xana doesn't understand The Power of Friendship, so his world is not good enough to fool the others as to who is the real Jérémie. He gets really mad at them for being "illogical".
- The Power of Friendship: Ulrich, Odd and Yumi all explicitly say this is the one reason why Jérémie would use a scanner despite his immense fear of being virtualized, something which XANA doesn't find logical.
- Smoke Out: Aelita induces one to help Jérémie escape from Jean-Pierre Delmas and Jim, so he can go to the factory to help her and their friends.
- Suddenly Voiced: XANA is able to speak through his surrogate, possibly reinforcing to the heroes how much better it is when he's quiet.
- Weaksauce Weakness: Comparatively to other Lyoko threats, the fake world's barrier on the outside can be deactivated by Aelita using creativity to disrupt it.
- Women Are Wiser: During their time trapped in XANA's fake world, Yumi is the only person who is suspicious of "Jeremie" and refuses to get into the "scanners" when he instructs them to. Ulrich and Odd, despite noticing some strange things, are still ready to trust him and only hesitate when Yumi finally speaks up about how "Jeremie" seems off.
