In the morning, Jeremie and Aelita look over the incident and Jeremie wonders if he just imagined it. Meanwhile, the school is lively as a rumour is spread about the arrival of a celebrity reporter nicknamed Thomas Vincent (TV), hoping to do a documentary on the kids and their academics. Odd is frantic, desperately searching for one of his DVD's of his short films, wanting to show him one of his films in a chance to be discovered.
When the man arrives with his camerawoman, he is rude and pretentious towards the teachers. He interferes in Suzanne Hertz’s class without authorisation and lets Odd down when he tries to hand him his DVD, obsessed with his own story.
During recess, a tower is activated and the heroes go to the factory. They don’t meet much resistance from X.A.N.A. and destroy the monsters without difficulty. Just as they reach the tower, it suddenly deactivates itself. Once back on Earth, the group meet back up with Jeremie, who tells him that the same cycle has repeated itself in other sectors. Believing something to be wrong, Aelita and Jeremie choose to stay on site to check the state of the Supercomputer, dismissing their friends to return to school.
During lunch, TV cuts in front of the line and takes all the remainder of food Odd was hoping to get and soon complains about the taste. In the lab, an anxious Jeremie spots another tower activating and remaining as such. This time, it looks like X.A.N.A is attacking. Back at the school, everyone notices how it has randomly started snowing, much to their joy. After some time enjoying the weather change, the temperature decreases suddenly to a whole new drop and bcomes a storm in record time. They all head into the school for shelter in the boiler room and are given proper clothes for the cold, all the while the temperature drops about -20°C (-4°F). Yumi calls Jeremie to tell him of the news, confirming his theory.
Despite the intense, bitter cold and the torrential snow, the three friends decide to make their way to the factory. Outside, they run into TV along with Herb and Sissi, who were in TV's car when it ran into a tree. Yumi demands TV take Herb and Sissi to the school for proper shelter. After they leave, a tree suddenly falls in their path. Yumi knocks Ulrich out of the way, taking the blow and impact herself. Unable to get her out, Ulrich tells Odd to make it to the factory on his own while he stays with Yumi. Odd wishes him the best and leaves as Ulrich looks in a nearby shed for tools to help Yumi. During this, the temperature approaches -40°C (-40°F).
Inside said building, Aelita insists to Jeremie that she must go to Lyoko, despite knowing that X.A.N.A is planning to use the Scyphozoa on her. Jeremie insists they avoid giving X.A.N.A what he wants, but Aelita tells him if they don't then their friends will die in the cold. He relents, and she goes to Lyoko and arrives in the Ice Sector and leaves for the tower on the Overbike. On Earth, Ulrich’s efforts to free Yumi are in vain and Yumi remains in beneath the trunk. Slowly, she begins to fall asleep as Ulrich tries his best to keep her awake.
On Lyoko, Jeremie detects flying monsters on Aelita’s heels. She turns and sees that Mantas following her, outside of Sector 5. They realize that X.A.N.A. has had an increase in power. The rays bombard Aelita with their mines and, in an attempt to avoid them and the Scyphozoa, she ends up falling to the ground. She looks up and the Scyphozoa begins moving towards her.
Odd then arrives inside the factory, practically frozen and near unconsciousness from the cold. Jeremie places him in a scanner and sends him to Lyoko just in time to save Aelita. During this, Yumi is slowly losing consciousness as the temperature continues to drop. A desperate and tearful Ulrich holds onto her in an attempt to keep her awake, all the while insisting that he needs her. After a difficult time, Odd finally manages to drop Aelita at the foot of the Tower. After dropping her off, he turns to attack the monsters, only to end up devirtualised.
Aelita runs into the Tower and enters the Code Lyoko, stopping the drop in temperature. After the weather returns to normal, Ulrich checks on Yumi. However, she fails to respond to him and Ulrich cries in distress. Odd returns to the lab and orders Jeremie to launch a Return to the Past to save Yumi. Jeremie does so, saving Yumi and the entire city just in time.
Starting the day again, the heroes don’t miss the opportunity to embarrass TV. When he disrespects Rosa Petitjean, Odd silently encourages her to stand up to him. She then dump a stock of meatballs on him, while the whole group laughs at him.
- The original French name for this episode is Guerre froide.
- Chronologically, this episode takes place after the events of both Temptation and A Bad Turn. However, it is aired before either.
- Though Principal Delmas is very strict at times, in this case, when it starts to snow lightly and Jim tells everyone to stop throwing snowballs, Jim gets hit with one, and Principal Delmas is looking the other way, proving that he threw it.
- This is one of the few episodes where Jim shows his kind side; he tells everyone to get back inside again (albeit in a more urgent manner, as if panicking), helps a little boy out of the snow, gets a fire going in the boiler room and later tells the children a story to get everyone's minds off of the bitter cold.
- From this episode onwards, Mantas are able to leave Sector 5.
- The title is referring to the Cold War, a period of social changes in relations and conflicts between Eastern sides (Soviet Union) and Western sides (USA).