The story opens during gym class, the class are picking teams and Jeremie is picked last (as usual). Upset, Jeremie runs out of the gym with Odd and Ulrich following him. Outside the gym, Odd and Ulrich try to cheer Jeremie up however he sulks away. Later, in his room, Jeremie is scanning Lyoko for William or an activated tower before he gets angry at himself for hoping for an X.A.N.A. attack. A few moments later, Aelita enters the room and asks if he was alright after hearing the story from Odd and Ulrich. Jeremie however shouts at her stating that she had fun on Lyoko while he stayed sitting in his chair, the four-eyed know it all, realising what he had just said, he leaves with Aelita standing stunned.
In the Factory, Jeremie is sitting in one of the scanners, angry with himself for shouting at Aelita and for losing his temper with Odd and Ulrich. In the Lab above a rat is on top of the computer interface when a spectre possesses it with X.A.N.A. The rat begins to attack the cables on the keyboards, this causes the scanner that Jeremie is sitting in to activate and virtualize Jeremie. Jeremie lands unconscious in a new sector, the Volcano Replika.
At Kadic, Aelita meets up with Odd and Ulrich, she asks about Jeremie however they said she couldn't find him. Yumi then arrives and states that she had looked everywhere for Jeremie, Ulrich then suggests that they go and search Jeremie's room. When they arrive, they find the room empty and as they begin to wonder where he went, Aelita spots that the Superscan has located an activated tower, the team conclude that Jeremie must be at the factory.
In the Volcano Sector, Jeremie throws rocks at a set of strange monsters. They flee and cower behind some rocks, Jeremie begins to communicate with them by asking them to move to answer simple questions. Soon he makes friends with the monsters who appear to be X.A.N.A.'s early designs and have been left to rot in the sector, suddenly William arrives. Jeremie attempts to greet him, but William tells him to be silenced and savagely attacks his new friends.
At the factory, Odd, Ulrich, Yumi and Aelita arrive at the Lab to find the door jammed (as the rat had chewed the cables). Meanwhile William begins to attack Jeremie when the group of monsters come out to defend Jeremie. In the lab, Odd and Ulrich manage to force the doors open and take care of the rat. On Lyoko, William easily dispatches the monsters and turns on Jeremie, just as he is about to attack, Aelita's voice calls out. Jeremie hurriedly replies and Aelita realises that he is on Lyoko and as he had been virtualized by a rat, his virtual incarnation was incomplete.
Aelita quickly virtualizes Odd, Ulrich, and Yumi to the Volcano Replika, Jeremie tells Odd to devirtualize him so he can return to the Lab, Odd quickly devirtualizes him while Yumi and Ulrich attack William. Jeremie quickly takes his position in the lab and Aelita heads for the Scanner Room. On Lyoko, Ulrich is dueling William however he looses and gets devirtualized, Yumi continues to attack with her fans. Jeremie virtualizes Aelita close to the tower, William spots this and hurls his blade at her, Yumi however takes the blade and is devirtualized, to William's fury.
Aelita enters the tower and enters the Lyoko code to deactivate the tower. William, infuriated by his defeat, dives into the Digital Sea, swearing revenge. Jeremie then launches the Return to the Past. It's gym class and the class is playing basketball, in the end although Jeremie's team lost the match Odd, Ulrich, and Jeremie all laugh much to Jim's confusion.
About the characters
- Only appearance of a comic-only character: Todd.
- Jeremie is bothered by his poor performance in sports.
- William apologises before devirtualising Yumi.
- Jeremie is virtualized on Lyoko, but his Lyoko form is not shown.
- The Return to the Past is seen on Lyoko as well as in the real world, which has never been shown in the series.
- Only appearance in the whole series of deformed monsters. It is revealed that X.A.N.A.'s monsters went through design stages and that the Volcano Sector was a place of banishment for the rejects.
- Although he was virtualised against his will, Jeremie should have had his subconscious analysed and ended up in a virtual form instead of his Earth one. This may be due to a bug in the virtualisation however, as it was performed by a rat.
- The activated tower's halo is blue instead of red.
- Just after devirtualising Jeremie, Odd is no longer on Lyoko, but wasn't devirtualised, and Jeremie forgets to mention him when he tells Aelita that Ulrich and Yumi need help.
- At the end, Jim's pants are red instead of dark blue.
- Odd's hair splotch disappears in certain panels.
About the series
- The X.A.N.A.fication of a rat was used in episode 11 of Season 1 "Plagued".
- The Volcano Sector was never in the series and didn't exist. It's a bonus from the Wii game.
- Ulrich: “You're not exactly Tony Parker.” Tony Parker is a French basketball player, previously a rapper.
- French title: Le meilleur des deux mondes
- Illustrator: Ullcer
- Colouring: Ullcer/Janse
- Supervision: Fabrice Saperlosky/Full FX
In French, this was titled "Le Meilleur Des Deux Mondes."