The episode starts in Sector 5, as Aelita is gathering data in the Celestial Dome while Yumi, Odd, and Ulrich are protecting her. Aelita finishes and uploads the data to Jeremie. The group then proceeds out of Sector 5 to get devirtualized. The Lyoko Warriors all convene in the lab as Jeremie is confident about the data being able to decrypt Franz Hopper's diary. Jeremie stays at the factory while the others head back to Kadic Academy. At lunch, Odd receives a text message from an unknown girl telling him to meet her in the woods. Jeremie then realizes that a tower has been activated and calls the group to tell them to come back to the Factory. Meanwhile, Odd heads to the woods and realizes that the text was a trap as a spectre was waiting for him.
Aelita, Yumi, and Ulrich get to the factory and get virtualized. Just then, Odd arrives at the lab and gets into one of the scanners and also gets virtualized. However, Jeremie detects a bug during Odd's virtualization and, surprisingly, the activated tower becomes deactivated. With the tower deactivated, the Lyoko Warriors decide to activate their own tower to launch the decryption program. The Warriors start noticing Odd acting strange as Aelita heads into the tower to run the program. Suddenly, three Tarantulas appear outside of the tower and the gang discover that Odd was a polymorphic clone. We then see the real Odd trapped in a well at the Hermitage with a hose spraying water down in an attempt to drown him. Yumi to devirtualized and goes to help Odd while Ulrich is chased by the clone. X.A.N.A starts attempting to take over the tower to try and erase Franz Hopper's work in the supercomputer.
Ulrich makes an attempt to sever the cables to shut the tower off, but is stopped by the clone. In the end, Ulrich defeats the clone but ends up being devirtualized by a Tarantula. Yumi makes it to the Hermitage and shuts off the hose. She the same tries to pry off the metal grate off the drain while Odd struggles to breathe. Suddenly, from out of nowhere, on Lyoko, Franz Hopper himself manages to overpower X.A.N.A and take over the tower. Yumi manages to pull of the grate and rescue Odd as Aelita is devirtualized back to Earth. The Warriors, now in Jeremie's dorm room, finally have their suspicions confirmed, as Jeremie tells them that Franz Hopper did once live on Earth and that he was the one who created X.A.N.A while building Lyoko. Jeremie then tells them that Hopper also had a daughter, who was transferred onto Lyoko with her father. Aelita finally realizes that she isn't an artificial intelligence, but is actually Franz Hopper's daughter.
This episode contains examples of:
- Bait-and-Switch: Much of the drama after the team is virtualized comes from the idea that XANA has managed to overcome the resistance virtualized members of the group have to his Demonic Possession without needing a Hypno Trinket or other kind of loophole due to Odd's behavior. It ends when we see the real Odd in a storm drain, confirming that in truth, a Polymorphic Spectre was virtualized in his place.
- Bare-Handed Blade Block: How Ulrich manages to recover his blade from his clone.
- Big Damn Heroes: Just when XANA took control of the tower, and was using it to gain access to the restricted part of the supercomputer where Jeremie kept important data, Franz Hopper manages to take control of the tower from XANA, and makes the decryption program go full speed.
- Comically Missing the Point: When told that Odd is meeting a "mystery girl" in the woods, Jeremie seems to miss the "mystery" part and asks who she is.
- Continuity Nod: Yumi mentions that XANA "doesn't like it when we play with his toys", to which Jeremie says that they have no choice. This references a prior episode where Jeremie used a tower for the teams' advantage.
- Failed a Spot Check: Ulrich forgot all about the last Tarantula guarding the tower, which leads to him being devirtualized by said Tarantula.
- Game-Breaking Bug: The decryption process won't shut down due to using too many resources, no matter how many times Aelita presses the stop button.
- Honey Trap: Odd falls for a "mystery girl" in the woods, and ends up in a rapidly filling storm drain at the Hermitage.
- Hope Spot: Odd is saved from his watery prison, and Ulrich is about to cut the wires to the tower...and the tarantula shoots Ulrich, devirtualising him, and XANA succeeds in taking over the tower, albeit temporarily.
- Hypocritical Humor: Ulrich compares Odd's love life to something out of a soap opera when the latter gets called to the woods by a "mystery girl", despite the rather dramatic complications of his own. Odd is more than willing to call him out on the spot.
- KidAnova: Mentioned by Odd again, and is the reason he's so cocky the first portion of the episode.
- The Mole: Odd is replaced by a Spectre for most of the episode.
- Mirror Match: Ulrich fights an evil clone of himself.
- Near-Villain Victory: Had it not been for Franz Hopper taking control of the tower, XANA would've taken all of the diary notes, and would have destroyed all of Jeremie's resources in the supercomputer.
- New Powers as the Plot Demands: Jeremie can use phone towers and use them to work out the approximate location of Odd's phone. Lampshaded by Yumi, who's surprised Jeremie can do this.
- Race Against the Clock: The storm drain fills up slowly but surely, and it's up for Yumi to find Odd in time, the catch is, is that Yumi doesn't know about the water for most of the episode.
- Tempting Fate: Ulrich says to XANA that Odd has never beaten him in combat, to which XANA responds by turning the Odd clone into an Ulrich clone.
- The Reveal: Jeremie tells Aelita was in fact, a real girl; Hoppers' daughter. Everyone is shocked by this revelation.
- This Cannot Be!: A heroic example: Aelita exclaims, "But that's impossible!" when Jeremie keeps looking at her, knowing that she's Franz Hopper's daughter.
