Now that X.A.N.A. has gained 95% of its strength, Jeremie and the others are intent on putting an end to the rouge multi-agent system once and for all. However, their efforts to activate their anti-virus are in vain as there are quickly beaten and devirtualized.
Until they can be re-virtualized, Aelita is called to Mr. Delmas' office, where she is disturbed to come face-to-face with Tyron himself. He reveals that had been married to her mother for four years now, and that he is now her stepfather. He bargains with her: put a stop to her friends' anti-virus or never see her mother again. Aelita refuses and escapes with Yumi to the lab. Jeremie alerts them of a G.P.S. locator that is giving their location to one of Tyron's subordinates. Aelita goes to the Cortex while Yumi leads them far away from the factory. Ulrich and Aelita enter the heart of the Cortex; ready to infect their virus to obliterate XA.N.A. from Tyron's supercomputer. Furious, Tyron orders that his supercomputer be shut down, which would casue the Cortex to disintegrate and for Aelita, Ulrich, Odd and William to be lost forever in the digital sea.
Aelita comes out of her daydream about her long-lost mother to answer to the other Lyoko Warriors. She's positive that she will find another way to contact her mother, even with Tyron's supercomputer destroyed. And given the enormous threat X.A.N.A. poses to the entire world, Anthea could only be proud of Aelita for her decision. Her mind is made up: they will destroy the Cortex that very same day.
All six members of the gang set off for the Cortex. When they arrive, William is forced to stay behind to guard the Skidbladnir while the others get to the Dome. Tyron has modified the Cortex's environment, meaning it will not change as they cross the terrain, but it shouldn't make a difference when they use the virus. William is given the green light to follow after the MegaPod using Super Smoke.
But it's not going to be easy: X.A.N.A. spots them and sends in three Mantas. Aelita and Yumi disembark from the Megapod to fight them while Odd and Ulrich stay and use the cannon, but the vehicle is quickly destroyed, along with Odd and Ulrich. William arrives to help and the three remaining Warriors push on to the Dome. Aelita opens the door, but is devirtualized soon after and Yumi is left alone. The door slowly closes just as she reaches it. She angrily turns around to face the Manta, which flies away, proving their "ultimate mission" as the ultimate failure. And now the five must wait for twelve hours to be virtualized again.
The next day, Aelita receives a call from Jeremie. The others are waiting for her at the factory. But as she leaves her room, she runs into Jim, who tells her that the principal wishes to see her. When she arrives, a man is waiting for her at the desk. Aelita recognizes the man instantly as Tyron and begins to back away, but Jim stops her. Tyron smiles back. The principal says that Aelita should be happy to learn the news the man brings: Her long-lost mother is alive. Tyron reasons that she is probably just in shock from the news; suddenly learning that her mother is alive, and also remarried, which makes Tyron her stepfather and legal guardian.
Back at the factory, the others are getting impatient. Yumi goes to look for Aelita while the others wonder if she possibly changed her mind about what they were about to do. They decide to wait on the Cortex to find out.
According to Tyron, he and Anthea have been married for four years, making him Aelita's legal guardian. He can take her back to Switzerland to see her mother again… but Aelita refuses, much to Delmas' confusion. Tyron presents her with a tablet which Anthea recorded a message for her daughter on. She says she's very happy to know that she's alive, and that Aelita can trust Tyron to reunite them. Tyron hands her a circular silver locket with a photo of a young Aelita and Anthea inside. However, there's a catch: Aelita can only see her mother again if she agrees to contact her friends and tell them not to destroy his supercomputer and the Cortex. Much to his surprise, Aelita adamantly refuses, as X.A.N.A. is far too dangerous a threat to all of humanity.
Yumi suddenly bursts in and discovers Aelita with none other than Tyron himself. She and Aelita flee, and Tyron calls his chauffeur to help him look for them in the park with a GPS device tracking hidden in the locket Tyron had given to Aelita. Yumi takes the locket (from which Aelita removed the photo) and walks around the park to lead the men far away from the lab while Aelita heads to the factory. Aelita later is virtualized next to the Skid, and she and the boys set off on their respective vehicles. They make it to the Celestial Dome of the Cortex without any trouble from either the Ninjas or X.A.N.A.'s monsters.
Yumi wanders through the park, examining the locket now and then. She is suddenly grabbed by Tyron, who snatches the locket from her hand. The chauffeur arrives and restrains her, and Tyron furiously tries to interrogate her about Aelita and the others' exact location. Yumi, however, says nothing. Tyron makes a phone call, therefore ordering one of his associates to shut the supercomputer down immediately, very much to Yumi's shock and horror.
Aelita and Ulrich enter the Dome while Odd and William stand guard outside. When they reach the interface, the orbicular Heart of the Cortex begins to dim. The platforms around them slowly start to float down towards the floor. The supercomputer is being shut down! Aelita works on, opening a path for the virus. If they don't succeed, Tyron will just wait a while and turn it back on again. The path open, Jeremie tries to bring them back in, but nothing happens. The shutdown procedure is blocking their virtual signals. The four warriors are forced to flee as fast as they can to escape permanent de-virtualization in the digital sea.
Outside the Dome, the central platforms also begin to gradually fall. They have to make it to the Skid, or they'll be lost in the Digital Sea forever. They board their vehicles and hurry to the Skid. All around them platforms descend and fall, causing a few near misses. Ulrich and Aelita fall, the Overbike devirtualised, but they are saved by Odd and William. All four continue on foot, they almost reach the Skid. The platform tips, creating a steep slope. They all slide down it and off the edge. The whole Cortex sector disintegrates into nothingness, and the three scanners do not open...
A horrified and tearful Yumi cannot believe her ears. Tyron and his chauffeur leave her standing rooted to the spot in sheer shock. After a moment of silence, she sprints to the factory, tears forming in her eyes.
She is welcomed to the Lab by everyone else, all safe and sound. The virus was indeed transmitted, but did not take full effect due the Cortex's quantum supercomputer being shut off. It will destroy the supercomputer once it's turned back on again, unless Tyron succeeds in developing an anti-virus system and stop it from working, therefore revitalizing X.A.N.A. once again. They too must turn their Supercomputer off. But they will always be ready for whatever may happen in the future and will always stay together as a true family.
The Lyoko Warriors assemble behind the control panel. Jeremie says the words "You lost the game, X.A.N.A.", removes the key and their supercomputer descends into the floor of its chamber and the lights go out; one by one.
- It has not yet been official whether a second season (Season 6) will be produced; though fans are desperately begging for one, as many things remain unresolved and questions sill unanswered.
- This episode had ended as cliffhanger, ending on a suspenseful note.
- The original French title for this episode is Ultime Mission.
- The Catalan subtitles for this episode can be found here: Ultimate Mission: Catalan Subtitles
- During the key removal scene, the camera stays on the keyhole for a few frames too long. If you pause it there, you will see that the key terminal is actually a modified Nintendo 64, pictured to the side.
- The title refers to what should have been their final mission in destroying X.A.N.A. and Tyron's supercomputer once and for all, which had partially failed.
- This is so far the only episode where both the Skidblanir and the MegaPod have been destroyed at the same time.
- This episode marks the third time the Supercomputer has been turned off by all of the Lyoko Warriors. The first time was in False Start and the second time was in Echoes.
- This is the third time the Skidbladnir was easily destroyed. The first time was by the Kolossus in Down to Earth, the second time was by the sharks in Jeremy's Blues.
- Out of all 26 episodes, Jeremie and Aelita are the only characters who XANA hasn't made a specter in their form.
- All five Lyoko Warriors were virtualized at the same time. However there're only three scanners in the factory.
|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|