Replika.The group travels to one of X.A.N.A.'s replica sectors in the Digital Sea. Meanwhile, Aelita and Odd get into a fight after Odd's desire to sleep in gets them both in trouble. Furthermore, their arguing inadvertently leads Nicolas and Herve into the factory, where Jeremy is forced to distract them while the group explores the Lyoko copy, which consists entirely of the Forest Sector. On the Lyoko replica, William and a pair of Megatanks arrive to destroy the Skid, the destruction of which would cut the group off from the Supercomputer. Odd and Aelita refuse to work together when they first arrive, but eventually resolve their differences and take William down. Jeremy surmises that another supercomputer is controlling the Replika (what the Lyoko copies were dubbed as), and in order to get rid of it, he'll have to find a way to materialize his friends at the location of the supercomputer.