Virus

Jeremy tries to create a virus to destroy the Cortex, however it doesn't work and the group discusses what to do. They decide to bring Laura to the factory and Odd steals her tablet and runs, with Laura chasing after him. When she gets there the gang explains about XANA and the Cortex and that they need her help, which she accepts to give. She easily fixes the problem and they launch the virus and a return to the past. Laura forgets everything, but thanks to a few hidden commands in the virus, the code for the return to the past was altered to exclude Laura, causing Laura to start having memory flashbacks of her time in the lab. She follows the memories to the sewers. William (who was left on Earth) tries to stall her, but fails, and Laura ends up back at the lab.
Meanwhile, Ulrich and Yumi encounter Ninjas in the Cortex for the first time, but are unable to defeat the new monsters and are sent back to Earth in no time. Laura agrees to keep the factory a secret and to help them out with programming to destroy XANA once and for all when they need her. With little choice, they welcome her into the group as the seventh member of Team Lyoko, which she gladly accepts.