Code Lyoko - Season 2 - Eps 24: Contact
During a short film made by Odd and starring Sissi, Sissi seems to be possessed by a ghost. She does not act as expected, however. Instead, she starts speaking in some strange language, focusing on Jeremie as she does. She is taken to the infirmary as a result. Later on, she walks into Jeremie's room and writes some code on a piece of paper. Jeremie translates the code, revealing a message stating a desire to help. Sissi is sent to the hospital after this, forcing Odd and Yumi to go there and collect her. On a trip to Lyoko, Aelita and Ulrich discover a white tower. Xana isn't happy about the tower, and sends Megatanks to shut it down forcibly. At the same time, it activates a tower and possesses a nurse at the hospital to do the same to Sissi. Odd and Yumi are able to prevent the nurse from doing so. They bring Sissi to the factory to finish the message she started earlier. She manages to type most of it out before Xana succeeds in shutting down the white tower. After Xana's tower is shut down, Jeremie translates the message, revealing that Franz Hopper had activated the white tower.
About Code Lyoko

Title: Code Lyoko
First Air Date: 2003-09-03
Last Air Date: 2007-11-10
Status: Ended
Rating: 7.463/10 (from 81 votes)
Language: FR
Seasons: 5
Total Episodes: 95
Network: France 3
Genres: Sci-Fi & Fantasy, Animation, Comedy, Action & Adventure
Production Companies: MoonScoop, Antefilms Production
Synopsis
Four children travel to the virtual world of Lyoko to battle against a sentient artificial intelligence named XANA, with a virtual human called Aelita.
Cast

Raphaëlle Lubansu
Jeremie Belpois / Odd della Robbia (voice)

Géraldine Frippiat
Yumi Ishiyama (voice)

Marie-Line Landerwijn
Ulrich Stern (voice)

Sophie Landresse
Aelita Schaeffer (voice)

Mathieu Moreau
William Dunbar (voice)

Carole Baillien
Sissi Delmas (voice)