Season 1

The very first season of Code Lyoko originally aired from September 8, 2003 to February 25, 2004. The head writer was Sophie Decroisette. It was directed by Jérôme Mouscadet.

Plot

The first season of the series focuses more on character development than plot development, only revealing details about the plot in its last few episodes. The rest of the episodes are "filler" because, in each episode, the Lyoko Warriors discover a X.A.N.A. attack, fight against it, stop it and activate a return to the past for one single day.

As a complement to avoid the monotony of the series, this season shows relationships between characters and other students and teachers of the school with their parents, relatives, etc. During all this, Jeremie is working on a program to "materialize" Aelita (transport her from the virtual world to the real world) so that they can turn off the supercomputer and, therefore, X.A.N.A. once and for all.

Story

X.A.N.A. Awakens

As Jeremie Belpois is looking for parts to use for his robots in an abandoned factory, he eventually finds the supercomputer and restarts it. Aelita awakes almost immediately afterwards, but didn't remember anything about her past. Jeremie assumed she was an artificial intelligence and decided to name her Maya, after she requested to be called something other than "Artificial Inteligence". As Jeremie found out about the scanners and virtualization, he sent Odd Della Robbia and Ulrich Stern to Lyoko. They didn't meet Aelita because they were devirtualized by Bloks in the Ice Sector, but not before Ulrich spots a strange red Tower in the same Sector. Feeling the pulsation from the red tower, Aelita heading to the Ice Sector through a Way Tower.

Jeremie wanted to fully materialize Aelita on Earth, so they can shut down the supercomputer and neutralize X.A.N.A. for good. He had confided in Odd, Ulrich and Sissi that they could do it if they could get Aelita into the red tower (a tower which X.A.N.A. had activated when Jeremie restarted the supercomputer) in the Ice Sector. However, Sissi gets electrocuted by an electric energy orb sent by X.A.N.A. and Ulrich brings Yumi Ishiyama to the factory. Jeremie sends Ulrich, Odd and Yumi to Lyoko to help Aelita get to the tower after an fierce fight with X.A.N.A.'s monsters. As Aelita saw the interface, she found out that her name wasn't Maya, but Aelita. She deactivates the tower. However, Jeremie's theory was wrong as Aelita didn't come to Earth. Aelita thinks that keeping the supercomputer on is too dangerous and that they should shut it down immediately, but the others agreed to keep fighting X.A.N.A until Jeremie finds a way to materialize Aelita. (X.A.N.A. Awakens)

Aelita's Materialization Program

Jeremie programmed an almost working version in Cruel Dilemma. But it wasn't until he left, and Odd accidentally pressed a few keys that weren't known, which made the program workable. Since nobody knew the full contents of the program, it couldn't be recreated. For an unspecified reason, it wasn't re-usable. Because of these two facts, it was a single-use program. Yumi fell into the Digital Sea later in the episode, and they had to use the program on her instead. This version was the only Materialization program that was able to recover a body from the digital sea. Unlike the later versions, it didn't require the target to be in a Tower to work. In Just in Time, Jeremie managed to create a materialization program which actually worked. Since he was unsure if it would work correctly or not, he tested it by materializing a single hair of hers. This worked, but in the process, his program bugged up the Annex Program, so that if Aelita used Code: Lyoko, she would be deleted. Exactly that happened, so the group used the hair to clone her and recover her data. In Frontier, when Aelita and Jeremie try to do more tests on materialization, Aelita accidently does some preparations that Jeremie had already done, causing Jeremie to get mad at her. As Jeremie thinks he hurt Aelita, he decides to go into Lyoko by himself, but an error occurs, moving Jeremie somewhere between Lyoko and Earth. Aelita, who is connected to Jeremies' thoughts, activates four towers from four sectors, bringing Jeremie safely back to Earth just before the supercomputer had him erased. During Ghost Channel, Odd, Yumi and Ulrich dissappeared during Return To The Past. Aelita finds out that X.A.N.A had created a virtual reality to trick the missing trio into thinking that they were actually back in the real world. As Jeremie virtualized himself to save the others, Aelita used her abilities to destroy the illusion, freeing the others from X.A.N.A.'s mercy. (Cruel Dilemma, The Girl of the Dreams, Just in Time, Frontier, Ghost Channel)

Aelita is finally Materialized

In Code: Earth, Jeremie soon manages to create the correct materialization program, sending Aelita to the Forest Sector. However, monsters attack her and the tower she is in in order to stop her from leaving. But with the help of Ulrich, Aelita materializes for the first time on Earth with others being at the scanner room to welcome her. Jeremie had her enrolled to Kadic as Odd's cousin and Yumi had her parents convinced about her staying at her home and Aelita was even better than Jeremie in the classes. But when team tried to shut down the supercomputer, Aelita collapses. As Jeremie investigated, he found out that X.A.N.A. had given Aelita a virus that connects them both. If X.A.N.A. is destroyed, so is Aelita. With X.A.N.A. sending his monsters to attack Kadic, Aelita deactivates the tower and decides to stay in Lyoko in case X.A.N.A. would attack again. The Lyoko Warriors decide that Aelita would visit the Earth occasionally to visit for them. (Code: Earth, False Start).

List of Episodes

Ep No.	Pro No.	Name	French Title	Airdates
0	000	X.A.N.A. Awakens, Part 1	Le réveil de XANA partie 1	US: October 2nd, 2006 FR: October 21st, 2006
0	000	X.A.N.A. Awakens, Part 2	Le réveil de XANA partie 2	US: October 3rd, 2006 FR: October 21st, 2006
1	101	Teddygodzilla	Teddygozilla	US: April 19th, 2004 FR: September 3rd, 2003
2	102	Seeing Is Believing	Le voir pour le croire	US: April 20th, 2004 FR: September 10th, 2003
3	103	Holiday in the Fog	Vacances dans la brume	US: April 21st, 2004 FR: September 17th, 2003
4	104	Log Book	Carnet de bord	US: April 22nd, 2004 FR: September 24th, 2003
5	105	Big Bug	Big bogue	US: April 23rd, 2004 FR: October 1st, 2003
6	106	Cruel Dilemma	Cruel dilemme	US: April 26th, 2004 FR: October 8th, 2003
7	107	Image Problem	Problème d'image	US: April 27th, 2004 FR: October 15th, 2003
8	108	End of Take	Clap de fin	US: April 28th, 2004 FR: October 22nd, 2003
9	109	Satellite	Satellite	US: April 29th, 2004 FR: October 29th, 2003
10	110	The Girl of the Dreams	Créature de rêve	US: April 30th, 2004 FR: November 5th, 2003
11	111	Plagued	Enragés	US: May 3rd, 2004 FR: November 12th, 2003
12	112	Swarming Attack	Attaque en piqué	US: May 4th, 2004 FR: November 19th, 2003
13	113	Just in Time	D'un cheveu	US: May 5th, 2004 FR: November 26th, 2003
14	114	The Trap	Piège	US: May 6th, 2004 FR: December 3rd, 2003
15	115	Laughing Fit	Crise de rire	US: May 7th, 2004 FR: December 10th, 2003
16	116	Claustrophobia	Claustrophobie	US: May 10th, 2004 FR: December 17th, 2003
17	117	Amnesia	Mémoire morte	US: May 11th, 2004 FR: December 24th, 2003
18	118	Killer Music	Musique mortelle	US: May 12th, 2004 FR: December 31st, 2003
19	119	Frontier	Frontière	US: May 13th, 2004 FR: January 7th, 2004
20	120	The Robots	L'âme des robots	US: May 14th, 2004 FR: January 14th, 2004
21	121	Zero Gravity Zone	Gravité zéro	US: May 17th, 2004 FR: January 21st, 2004
22	122	Routine	Routine	US: May 18th, 2004 FR: January 28th, 2004
23	123	Rock Bottom?	36^ème dessous	US: May 19th, 2004 FR: February 4th, 2004
24	124	Ghost Channel	Canal fantôme	US: May 20th, 2004 FR: February 11th, 2004
25	125	Code: Earth	Code Terre	US: May 21st, 2004 FR: February 18th, 2004
26	126	False Start	Faux départ	US: May 24th, 2004 FR: February 25th, 2004

Trivia

If one adds the 2-part prequel, then Season 1 would consist of 28 episodes rather than 26.
This was the only season of not made by Moonscoop. It was instead made by Antefilms, prior to their merger with France Animation.
This season had more English DVD releases than the other seasons combined. In fact, the entire season, has been released by two companies. In addition, 3 partial sets have been released.
Odd's only ability on Lyoko is "Future Flash," allowing him to see imminent danger to his friends or hidden paths. It is used only in four episodes and is lost after this season.
It is mentioned throughout the season that Aelita's presence on Lyoko is the only thing keeping X.A.N.A. alive. It is unclear at this time if X.A.N.A. is aware of this, however, since he frequently sends his monsters to try and kill Aelita.