Samantha Suarez, Odd's former sweetheart and girlfriend, enrolls at Kadic, and the boy eagerly pursues her. At the same time, he is being pursued by a specter.
Laura and Jeremy finally finish their virus. Laura is keen to implement it immediately and destroy both the Cortex and X.A.N.A., but Jeremy insists they wait.
The dislike between William and Ulrich keeps growing, but when X.A.N.A. creates a specter to attack Yumi, Ulrich and William have to put their differences aside and get Ulrich to the tower to deactivate it.
A new, highly intelligent and gifted teenage girl named Laura Gauthier tries to join the Kadic Academy. Unfortunately, Laura follows William to the factory and discovers the lab.
After successfully reprogramming the Skid, Jeremy and the four other Lyoko Warriors discover another Replika in the Digital Sea. They intend to learn more about this mysterious, ever-changing sector.