Just in Time.Taking a different approach to his research, Jeremy materializes a single hair of Aelita's. Unfortunately, the follow-up test goes awry, and Jeremy has to find out why. Meanwhile, different parts of the school begin to crumble apart. Jeremy 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. Jeremy 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 killed. After the return to the past, Yumi remembers that Jeremy said that the hair contained Aelita's entire computer code. Jeremy places the hair in the scanner, virtualizes it to Lyoko, and Aelita is inside the tower she deactivated.