A tower is activated while Odd is jogging in the woods. A spectre, in the appearance of an American football player, is sent after him to steal his source codes. Meanwhile Aelita and Ulrich go to deactivate the tower, but when they reach it, Aelita is unable to enter. The tower deactivated itself because Odd lost the last of his source codes to the spectre, raising X.A.N.A.'s power to eighty-five percent.
Odd then formulates a protection plan where the "codeless" protect the people who cannot return to Lyoko for twelve hours, and who have nowhere to hide from X.A.N.A.'s spectres. Another tower is activated, and Ulrich and Aelita are shut in a closet under Odd's protection while William and Yumi are sent to Lyoko. William seems upset about being referred to as "codeless," as it means he can't deactivate towers, and isn't considered as important as the others. When he and Yumi reach the tower they're confronted by an evil clone of William who plays on his doubts, telling him that he's just being used by the gang, especially Yumi. He and the clone then chase after Yumi while the footballer spectre finds Ulrich and Aelita and corners them.
Odd realizes that the sound system can be used to disrupt the spectre and stop it from advancing, so he starts singing Frère Jacques over the PA to delay it. Meanwhile, William turns on his clone, allowing Yumi to get to the tower and deactivate it.
- The original French name for this episode is Les sans-codes.
- Odd is the first Lyoko Warrior to lose all of his source codes, raising X.A.N.A.'s power to eighty-five percent.
- A William clone (possibly X.A.N.A. itself) makes its first appearance of the fifth season, trying to lure the real William over to X.A.N.A.'s side once again. This is also the first appearance of a Lyoko Warrior clone spawned in Lyoko in season five.
- Yumi uses her bo staff for the second time in the Desert Sector; the first time was in the Cortex.
- The group are shown eating in the cafeteria for the first time in the fifth season.
- Yumi got a little of her hair cut when William threw his Zweihander to annihilate a Kankrelat.
- William uses his energy blades twice in this episode.
|Code Lyoko Evolution|
|X.A.N.A. 2.0 | Cortex | Spectromania | Mrs. Einstein | Rivalry | Suspicions | Countdown | Virus | How to Fool X.A.N.A. | The Warrior Awakens | Rendezvous | Chaos at Kadic | Friday the 13th | Intrusion | The Codeless | Confusion | An Assured Professional Future | Obstinacy | The Trap | Espionage | False Pretenses | Mutiny | Jeremy's Blues | Temporal Paradox | Massacre | Ultimate Mission|
|Season 1 · Season 2 · Season 3 · Season 4 · Code Lyoko Evolution|