The episode starts in Carthage, 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:
- Honey Trap: Odd falls for a "mystery girl" in the woods, and ends up in a rapidly filling storm drain at the Hermitage.
- This Cannot Be!: A hero example: Aelita exclaims, "But that's impossible!" when Jeremie keeps looking at her, knowing that she's Franz Hopper's daughter.