|Air Date (US)||October 28th, 2005|
|Air Date (France)||January 25th, 2006|
|Written by||Laurent Turner|
|Storyboard by||Olivier Schramm, William Renaud|
|Preceeded by||Déjà Vu|
|Followed by||Is Anybody Out There?|
It's time for class physicals at Kadic Academy. The various students in the building are discussing their various problems, such as Herb's acne, Julien's near-sightedness, or Odd's scrawniness. Julien is trying to memorize the eye chart to avoid getting glasses. Odd still refers to himself as svelte. Sissi talks to Ulrich about how her medical record is perfect. Jeremie is talking to Aelita about her lack of any medical record or vaccinations. He's worried that they will learn that she, Aelita, is not completely human. She's sure everything will be fine, saying that Jeremie seems to find her human enough. The nurse calls in Jeremie, Julien and Odd to start.
In the nurse’s office, the nurse does little more than confirm what each already knew. Odd is indeed scrawny and Julien is not only near-sighted, but has a bad memory on top of it. Aelita and Sissi are next. Sissi finds out that she's five pounds overweight, not that she'll accept it as true. Aelita asks about her missing medical record, which Yolanda assures her won't be a problem. Meanwhile, Jeremie's computer picks up an activated tower. He has Ulrich wait for Aelita while he and Odd head to the factory. Yolanda is X.A.N.A.'s target and is possessed by X.A.N.A.'s ghost. A scream from Sissi alerts Ulrich to this, but Yolanda has already left with an unconscious Aelita.
At the factory, Jeremie is informed of Yolanda's possession. He locks down the elevator in an attempt to slow her down. Seeing as how they cannot deactivate the tower without Aelita, Jeremy has a new idea to try out. He is going to make his own ghost to possess one of his friends. That way, they can fight the X.A.N.A.-possessed Yolonda on equal terms.
On the factory floor, Yolonda arrives with Aelita. She finds the elevator disabled and heads for the access corridor. Ulrich shows up to delay her. X.A.N.A.'s victims always get stronger and more powerful with each possession, and today, unfortunately for Ulrich, is no exception. Yolanda has the incredibly strong and powerful energy-based ability and power to form bright yellow-colored glowing energy into huge concentrated beach ball-sized orbs to attack her enemies with. Ulrich is not much of a match for the continuous attacks.
Back in the lab, Jeremie starts his test by activating a tower in the mountain region. His activated tower is green instead of red like X.A.N.A.'s. He uses his own ghost to possess Odd. Unlike X.A.N.A.'s victims, Odd is in complete control.
Back on the factory floor, Aelita has managed to get away from Yolanda. She's trapped at the entrance to the corridor. Yolanda eventually knocks out Ulrich and heads back to get Aelita. As she does, Odd comes out from the corridor and attacks her. Both are evenly matched. Odd plays for time while Aelita and Ulrich escape.
In the depths of the factory, Yolanda and Odd fight to see who is better. Odd seems to do better at first, using the newfound abilities he just got, as if he had always had them. Yolanda is eventually sent into the water by an unusually strong and powerful orbicular bright yellow-colored energy blast from Odd.
After being sent to Lyoko's Forest Sector, the others head for the tower on their trademark vehicles. Along the way, they encounter a couple of Krabes. Ulrich slices one down the middle and Yumi takes care of the other. A Kankrelat shows up to attack Ulrich and lands a hit. However, it is destroyed just as quickly.
Back in the factory, Odd starts to slowly lose his energy orb/sphere-generating abilities and powers. He calls Jeremie to find out why. Jeremie is not quite sure, but not too surprised either. As Odd continues fighting, Jeremie loses control of the tower he activated to X.A.N.A. The effects translate to Odd, who loses all of his powers from the possession. Instead of controlling Odd, X.A.N.A. is just going to pump all of his life-force energy until it kills him. Powerless, Odd is forced to run, losing his cell phone to Yolanda along the way.
On Lyoko, the group is informed of Odd's situation. Aelita and Yumi head to the mountains. Ulrich stays behind to guard the other tower. A Krab is there, but it's easily destroyed by Ulrich. Three more Kankrelats arrive to join the fight. Ulrich uses his Overbike to wipe out all three in a single hit.
In the mountain region, X.A.N.A. has made the entire region invisible. All that can be seen is the thick fog. Similarly, his monsters are protected by the same effect. An unknown number of hornets take out Yumi's vehicle, causing both her and Aelita to plummet. Guided by Jeremie, they're able to catch a ledge. He continues to guide them across the unseen landscape. Eventually, they get close to the tower. This is when the invisible Hornets come back for round two. Yumi covers Aelita as she heads to the tower. The Hornets manage to force Yumi off the edge, but she grabs on just before falling.
Back in the factory, Odd is eventually knocked out by Yolanda. Knowing that he'll die anyway, she heads back to the corridor. Aelita manages to shut down the tower just before he dies.
Back on Lyoko, the landscape and monsters reappear. There was ground under Yumi the whole time, it seems. The two Hornets, now visible, are destroyed by her. Jeremie brings up the Overboard and they head back to the first tower.
In the forest, Ulrich has triplicated himself and is dealing with a Blok, a Krab and three Kankrelats. The Blok is the first to go. The Krab goes next. Alone, the three Kankrelats are no match for Ulrich. His two clones take out two in a flash. They torture the third by kicking it into the air before destroying it. Aelita and Yumi arrive as he fuses himself into one person again. When Yumi asks where the monsters went, Ulrich just asks "What monsters?"
Back in the lab, Yolanda arrives to cause trouble. Odd arrives, too, but isn't any match for her. Both Jeremie and Odd are about to get blasted when Aelita shuts the tower off. Yolanda's possession subsides and she collapses.
Back at the school, Sissi is trying to explain what happened, making sure to include the weird stuff in her story. Neither the principal nor Jim believes her. The whole story reminds Jim of when he used to work in a psychiatric hospital. As always, he'd rather not talk about it. The others show up with Yolanda so Sissi doesn't seem quite as crazy. Yolanda remembers nothing and believes Aelita's story of how she went out to get some air through the window. As the others walk off, Sissi demands an explanation. Odd wards her off by commenting her on her extra five pounds. Sissi is still in denial about it. Odd tries to tell her that no one's perfect, to which she responds by pointing out his scrawniness. Odd still insists he's svelte, ending the episode as he gets a good laugh from the others.
- The original French name for this episode is Au meilleur de sa forme.
- An animation error is made during Odd's physical exam scene. It is shown he has removed his shirt, but kept his purple pants. However, after stating he is "not scrawny" (I am svelte!) and walks away, you can see him in his orange pajama/boxer shorts.
- This episode is the first time someone other than X.A.N.A. activated a tower; in this case, it was Jeremie.
- This episode strangely implies that either Jeremie is stronger than X.A.N.A. or the Lyoko Warriors deemed immune to possession can be possessed if they have consented to be.
- This was the first episode that Aelita deactivated two towers without a return to the past.
- Yumi set the school record for 100 meter sprint with a time of 14.35 seconds in this episode.