Koushirou tries to use his laptop to tap into Etemon's Dark Network, but in doing so receives a mysterious email calling for help. The sender promises that if they come to help the sender, and then they will tell them where all the Crests are hidden.
While looking for the Chosen, Etemons Gazimon minions find an abnormality in an area with a pyramid. Etemon theorizes that it must be Nanomonnote , and decides to "pay him a visit".
The kids look for the email's sender in the hopes of finding a lead, and, on the way, Takeru's Tag begins to glow. They find Takeru's Crest in a nearby wall, and the kids take this to mean that it wasn't a trap and that the sender probably knows where the last Crest, Sora's, is. They follow the passage opened by the reception of Takeru's Crest, where Koushirou finds symbols on the wall similar to those in Andromon's factory and Kentarumon's ruins.
Koushirou finds one symbol that he didn't find on File Island and erases it, which turns the light on. Realizing that he can use the program to manipulate his surroundings, he gets the wall to pull up a map of the area. Jou is flabbergasted, saying that its not like theyre in a computer, but Koushirou says for all they know, they might be; data and programs take physical form in this world, and the kids wonder if this means that theyve become data and are no longer flesh-and-blood beings.
Combining the map that Gennai sent him with the program on the wall, Koushirou gets the map to pull up the entire globe's map; the world they're in is not only exactly the same as the Earth, but it also shares the exact same Internet network as Earth's. Since the email that came to Koushirou comes from a site that Koushirou had frequented often at home, Koushirou theorizes that the world theyre in is nothing more than data like that on a video game or computer, and that they may not be far from Earth in that theyre in Earths computer network itself.
The kids are understandably confused, but one thing is clear: they wont be able to return home until they finish what they have to do. They prioritize finding the person who sent the distress message, and Koushirou uses a program embedded in the mail to open a wall and send them towards where the sender is: a pyramid, which they, to their alarm, see Etemon entering.
During the night, Sora apologizes to Taichi for having them go through all this trouble for her Crest, but Taichi reassures her, believing that the revelation that theyre just data should cause them to take it easy, and that they shouldn't turn their back on anyone who needs help (more than ten years before Taiki, to boot).
In the morning, Koushirou tells Sora that because the data they're made up of is so complicated, taking damage in this world will probably transfer to the real world. Taichi, unfortunately, is out of earshot and quickly beckons Sora and Koushirou to come with him. The three of them and Jou, accompanied by their Digimon and sent off by the others with good luck wishes.
They reach the pyramid, where they successfully avoid a close encounter with Etemon, but Taichi continues to act recklessly, taunting Etemon and fooling around with some of the Gazimon minions. They quickly find the one who sent the email, Nanomon, who says that he once lost in a fight with Etemon, was imprisoned there, and was forced to operate Etemons Dark Network. Telling them that he knows where Sora's Crest is and that they share a common enemy, he asks them to release him, which after some deliberation the kids decide to do. Unfortunately, they're quickly caught by Etemon, who managed to catch them because of Taichi's antics.
Agumon, Tentomon, Piyomon, and Gomamon evolve, but are sitting ducks against Etemon. Nanomon breaks free of his prison and starts to use everything around him as weapons, showing no concern for the kids and their Digimon as his business is finished with them. About to lose to Etemon, Nanomon kidnaps Sora and Piyomon and runs off with them. Taichi tries to charge after them, but finds himself behind a passageway; he tries to charge through it, thinking that he's just data after all, but Koushirou informs him that he needs to find the correct way to enter first, and that Taichi will die if he dies in this world.
Taken aback by this revelation, and knowing that Sora and Piyomon have been taken away by Nanomon, Taichi becomes very afraid, even when Koushirou identifies the correct entry point. The situation is not made better when Etemon enters with an injured Agumon, Tentomon, and Gomamon, before they're saved by Togemon and Garurumon, whose human partners had spotted signs of fighting in the pyramid.
The kids retreat and run back to their hiding spot, where Taichi breaks down over the knowledge that he lost Sora to his own recklessness...
- Bittersweet Ending: The gang makes it out alive to the hiding spot, but Tai has an emotional breakdown over realizing he lost Sora on his own terms.