While Yumi and Aelita are on a mission in the Cortex, a tower is activated in the Mountain Sector. They're forced to abandon the mission and turn the Megapod around. William is the only one who's reachable; neither Odd nor Ulrich notice their phones ringing. Jeremie wants Aelita to continue the mission and Yumi wants to go to Earth to save Ulrich, but both are convinced that deactivating the tower is their top priority.
Odd is sitting against a tree in the park listening to music when Mr. Rouiller approaches him. The man doesn't respond to the boy's greeting. Odd notices X.A.N.A.'s symbol in the spectres eyes too late; his remaining source codes are stolen before the spectre moves on to its next victim. Odd calls to warn Jeremie.
On the Cortex, the Megapod is suddenly attacked by several relentless Megatanks. The vehicle's energy plummets as the monsters chase it down. Finally, the girls lose the Megatanks by hiding in a sort of alleyway, waiting there to discuss their next move. It will take too long for the Megapod to recharge, and the Megatanks have already found them again! Aelita and Yumi transfer out of the vehicle and flee upwards with the Overwing's help. Unfortunately, Yumi doesn't make it. Aelita arrives at the Skid alone and makes her way back to Lyoko.
As Yumi leaves the lab to look for Ulrich, Odd finds him meditating in the gym. When he goes into the locker room to collect his things, Ulrich is ambushed by the spectre and he too loses all his codes! With Yumi devirtualized, Aelita is now the only one who can deactivate the tower! The boys split up: Ulrich will search for Yumi while Odd goes to Lyoko to help William get rid of the Bloks.
In the Mountain Sector, William is found by the Bloks and a chase begins. He's severely outnumbered, and insists that he go to Earth to help protect Yumi. Jeremie disagrees, but William willingly stands in front of the Bloks unarmed, and is devirtualized. Odd arrives to take his place. Meanwhile, Aelita is being attacked by Kongres in the Digital Sea. Jeremie comes up with the idea of boosting the Skid's sonar to create a sort of shield around it, which would destroy any monsters it touches. The plan works and Aelita is free to get back to Lyoko.
At the school, Ulrich warns Yumi about the identity of the spectre over the phone. At that moment, it approaches Yumi, and her phone slips out of her hand. She runs. William joins Ulrich and they rush off to find their love together. Back on Lyoko, Odd is faring decently against the Bloks. He destroys two in the name of his and Ulrich's lost codes, but is then overwhelmed and surrounded when more of the monsters arrive. They corner him at the edge of the platform, bombarding him with lasers and threatening to throw him over the edge…
Ulrich and William discover Yumi's phone lying on the ground. Yumi herself is hidden inside a classroom, but comes out when she spots Ulrich. The spectre grabs her. Ulrich races in and pulls Yumi from the gardener's grip! But the digital being isn't finished yet… it reaches for Yumi… Aelita arrives on Lyoko just in time! The Skid rises up behind Odd and he jumps on top of the cockpit. Aelita activates the duel machine guns on the vessel, annihilating all the Bloks in no time flat before making her way to the tower.
The spectre explodes into a cloud of pixels with a loud scream. Yumi is weak, cradled in Ulrich's arms, but the side-effects mean that she still has some codes remaining… but it turns out to be a tiny amount. She and Aelita are the only ones left with codes, and X.A.N.A.'s power has climbed to 95%. They've reached their agreed limit for destroying Tyron's supercomputer.
Jeremie refuses, as they still haven't found where Anthea is yet. But Aelita insists: X.A.N.A. is a huge threat, one too big to risk. The A.I. could easily get the remaining source codes from Aelita and Yumi and take over the entire network. Even if Aelita did get to see her mother again, would it be worth it? All their lives are put in danger as long as X.A.N.A. lives. For the sake of her friends - her family - Aelita decides that it's time to destroy the Cortex.
- The original French name for this episode is Hécatombe.
- The Catalan subtitles for this episode can be found here: Massacre: Catalan Subtitles
- Final apperance of Lyoko in Season 5.
- Final tower deactivation in Season 5.
- Third and final time Aelita deactivated a tower in Season 5.
- The title refers to Odd and Ulrich losing the rest of their source codes, and Yumi losing almost all her codes in the one episode.
- X.A.N.A.'s power has now reached 95%, and Aelita is determined to destroy the Cortex rather than seek her mother out, as the risk is too great.
- Yumi and Aelita are now the only ones left who can deactivate towers.
- This is also the first episode where the Skid's weapons were used to attack a non-Digital Sea monster.
|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|