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.

一行人来到 X.A.N.A. 位于数字海的一个复制区。与此同时，Aelita 和 Odd 因 Odd 想睡懒觉而大打出手。他们的争吵无意中将Nicolas和 Herve带进了工厂,Jeremie 被迫分散他们的注意力，而大家则探索完全由森林扇区组成的 Lyoko 副本。在 Lyoko 副本上，William 赶来摧毁 Skid，摧毁 Skid 将切断小组与超级计算机的联系...

Les Lyoko-guerriers repartent en mission dans la mer numérique pour explorer un nouveau monde virtuel que XANA semble avoir créé sur le modèle de Lyoko.

Os Guerreiros de Lyoko regressam ao mar digital numa missão para explorar um novo mundo virtual que o XANA aparentemente criou baseado em Lyoko.

Odd no ha ido a clase y Aelita ha mentido para disculparle pero el resultado ha sido un castigo del director para los dos.Esto complica los planes para detener a Xana porque quieren explorar la esfera de la red con el nuevo submarino, cuanto antes.