Taking a different approach to his research, Jeremie materializes a single hair of Aelita's. Unfortunately, the follow-up test goes awry, and Jeremie has to find out why. Meanwhile, different parts of the school begin to crumble apart. Jeremie learns that his first test damaged Aelita's program, and she'll be deleted if she tries to deactivate a tower. On top of that, they learn that X.A.N.A. is responsible for the damage being caused to the school by using ultrasonic sound waves, which continues to get worse. Jeremie has to fix the damage he caused in time to save Odd, who ends up trapped inside the school with Milly, Tamiya, and Kiwi. Unfortunately, after two tries, both ending in failure, Aelita, with the help of Yumi and Ulrich, has to deactivate the tower or else Odd, Milly, Tamiya, and Kiwi will be done for. After the return back in time, Yumi remembers that Jeremie said that the hair contained Aelita's entire computer code. Jeremie places the hair in the scanner, virtualizes it to Lyoko, and Aelita is inside the tower she deactivated.
Elenco: Jodi Forrest , Allan Wenger , Paul Bandey .