Episode Title:
Lost at Sea.
Episode Description:
Hiroki steals Yumi's diary and Ulrich finds it. Meanwhile, in a new attempt to free William from X.A.N.A.'s evil clutches, Jeremy creates a program to find William in the Digital Sea. When he uploads the program to the Skid, the sonar becomes bugged, forcing the gang to return to Lyoko. When the Kongres interrupt their return, Yumi gets stranded, and is lost in the Digital Sea. X.A.N.A.'s attempt to take advantage of this alerts Jeremy, allowing him to direct his friends to Yumi. After fighting off the Kongres and William, who has his own ship (the Rorkal) to travel in, they return to Earth. To help Hiroki apologize to his older sister, Ulrich secretly returns the diary.
