In the library, Jeremie is explaining to Aelita why they must stay silent in the library, Aelita says "Oh you need silence to focus on what you are studying" and Jeremie says "Yeah and not miss game point." Ulrich and Odd are playing with a paper ball, to see who gets the match point, Odd stands up and hits it, Ulrich leans back, and holds on to the table with his leg and taps it and gets it to the other side, and he wins. But Ulrich loses balance and falls down. Jim comes and yells at him and tells him: "Ulrich! Is that what you call studying?!" Ulrich laughs, and Yumi is trying not to show Jim that she is laughing. The principal comes in and Jim grabs his ear, he doesn't notice it is the principal and let’s go. The gang starts laughing. The principal came to look for Jeremie, and he needs to talk to him.
In the sewers, the rat that has been possessed by XANA, bites the other rats, and XANA takes over them too, to build up a bigger army. Outside, Jeremie comes out and tells Ulrich, Yumi and Odd everything about what the principal tolled him. He says that the school psychology has been looking at his progress and that he is going to see that he gets moved to another school if he has a really high IQ. Odd says "Hold on! You mean he is going to send you to a school for future Einsteins?" Jeremie says "Yeah...", and that his folks aren't going to pass a great opportunity like that.
In the sewers, XANA has taken over a big army of rats; the main rat is commanding the other rats.
Outside, Jeremie and the gang are talking about how to flunk the test, so he doesn't get transferred into another school. Odd says "What’s the big problem? You flunk the test and they will think you are a total moron, no one will ever know!" Jeremie tells them that those kinds of test are full of trick question, and you need to be clever to flunk that test, Yumi says that he is the cleverest kid around so there is no reason to worry, and Jeremie tells them that he will try his best. Yumi leaves and tells Ulrich to keep her posted.
In the library, Jeremie is taking the test, as Ulrich and Odd go and eat. Meanwhile three rats cut the electrical wires and everything is dark. Sissi in her room says: "What kind of a two-bit school is this?" There is a pack of rats in her room, she manages to get away. In the cafeteria everyone is clowning around, Ulrich tells everyone to quiet down, then the rats come down from the ceiling and start to attack. The kids try to leave, but they are surrounded by rats outside. Ulrich calls Yumi and tells her to come to the school. Ulrich tries calling Jeremie but the psychologist doesn't let him answer.
At the cafeteria, the kids have made it outside using the extinguishers to scare the rats away. Sissi is on the other side of the rat army, but lucky for her, Yumi is coming on her bike, she gets Sissi, and goes to where Ulrich and Odd are. Jeremie calls Yumi and tells her that they will meet in the factory, Yumi tells everyone to go to the science building, everyone goes up to the roof. Yumi says "We have to get to the factory, Jeremie said he will meet us there!" Ulrich says "Great idea, but how do we get there?" Odd finds a hose, and they go down to the ground from the ceiling. They must go over the wall since the sewers are packed with rats.
At the Factory, Yumi virtualizes Ulrich and Odd, as Jeremie is going to the factory. On Lyoko, Ulrich and Odd don't see Aelita, Yumi realizes that she typed in the wrong coordinates, Odd says that it's okay, and that they will run. As they run, they see Aelita being chased by two Crabs. Ulrich says "Don't worry Aelita; your two nights in armor have come to protect you." As they close in, everything starts tilting. Yumi thinks it’s her mistake but Aelita says that Xana has changed the slope of the plateau. Odd, Ulrich and Aelita let go, but Aelita makes a place for them to land on using her creativity. The Crabs charge in right after them. The two Krabs shoot at Aelita, and Ulrich stands in front of her and takes the hits. Odd tells Ulrich to protect Aelita, that he will attract their attention. Odd destroys one Krab but the other shoots a rock he was holding on to, and he falls toward the Digital Sea, but the Krab devirtualizes him just in time.
Jeremie arrives at the factory, and tells Yumi to go to the scanners. At Kadic, the rest are on the ceiling and the rats have managed to get to them, and try to chew through the door. On Lyoko, Ulrich is protecting Aelita, but he gets shot twice. He tries to destroy the Crab, but it devirtualizes him. Just as the Crab is about to attack Aelita, Yumi destroys it. At Kadic, the rats have managed to open the door to the roof. Yumi takes Aelita to the tower. In the library, the psychologist says "Say...say cheese!", as a group of rats enter the room. Aelita enters the tower and just as the rats are about to attack the kids, Aelita deactivates the tower. Jeremie says "Return to the past now!" and they go back in time. After the return trip, the gang are in the library talking about the test that Jeremie is going to take. Yumi says: "Hey Jeremie have you figured out a way to flunk the test?" Jeremie replies by saying: "Well now that I know all the questions, I shouldn't have any problems giving all the wrong answers." Ulrich says: "Are you sure it’s going to work?", and Jeremie says: "I’ve got a foolproof way of flunking. I'm going get all my answers from Odd!" Ulrich and Yumi start laughing, and Odd says: "Yeah, yeah, laugh your heads off all you want, but who knows you might be in for a big surprise!" The episode ends on that.
This episode contains examples of:
- Blinded by the Light: The rats have this as their weakness, which Jeremie exploits after discovering it when his psychologist plays with a torch.
- Better to Die than Be Killed: Inverted, so it's more Better To Be Killed Than Die. Odd comes really close to hitting the void. As Cruel Dilemma showed, if they fall into the void, they die for real, and do not go back to earth. The only way to get back to earth at that point is to be materialised, But since Jeremie does not have working code for this process anymore (and is currently working on a redo), so it's fortunate Odd gets shot by a laser before he touches the sea of the void, thus killing him in a manner than forces him back to earth rather than stranding him in Lyoko.
- Ear Ache: Thinking a student just randomly came into the library, Jim grabs his ear and yells at him that he has a couple hours of detention when he realizes he just pulled on the ear of Mr. Delmas. The kids, understandably, find this amusing.
- Hive Mind: The Rat packs act like this, often moving in groups and thinking very similarly.
- Locking MacGyver in the Store Cupboard: The rats have swarmed the school to prevent people from escaping, however Odd uses a fire hose as a rope to climb down the science building, as does Ulrich and Yumi. Similarly, Jeremie uses photographers lights to blind the rats so he can, slowly but surely, get to the lab himself to relieve Yumi of his intended duties as Mission Control.
- The Most Dangerous Video Game: XANA modifies the terrain by rotating it to slip up the Lyoko warriors and Aelita. Aelita uses her creative powers Just in Time to create a wall to land on, as well as ledges for Odd to use later.
- Missing Mission Control: Jeremie is temporarily M.I.A at the lab due to being swarmed by a different pack of XANA-Rats, so Yumi, under the instruction of Jeremie, activates virtualisation scanners for Ulrich and Odd instead. Yumi does adapt decently well, but mishears 79 degrees west as 19 degrees west, and only realises the mistake after they arrive at Lyoko. It isn't a huge deal, as they both run to Aelita without much of an issue.
- Mundanger: The schools' psychologist has been keeping tabs of Jeremie's school progress, and wants him to take an IQ Test. He's sad because if he leaves the school, not only will Xana be free to destroy the world, but Jeremie will miss his friends.
- Obfuscating Stupidity: Jeremie tries this on purpose; it's not as easy as it sounds, which he tells the others before taking it that it's likely full of trick questions and such.
- People Fall Off Chairs: Ulrich falls over backward in his chair in the beginning of the episode after winning a game of paper-hand-ball at "match point" with Odd.
- Red Eyes, Take Warning: The rats possessed by XANA gain red eyes, and also gain Hive Mind sentience.
- Swarm of Rats: A Xana-possessed swarm of them attempt to destroy the school.
- Timeline-Altering MacGuffin: Since after the time rewind he knows the answers to the questions, and therefore how they are laid out, he decides to either answer wrong in the correct places, or just ask Odd the questions and uses his answers, which curiously Odd takes as a weird compliment.
- Why Did It Have to Be Snakes?: The psychologist is terrified of rats because he says once when he was a kid a rat came up to his room. He spends most of his screen time panicking once the swarm of rats attack.
