The now-empty Spiral Mountain suddenly begins to swirl with dark energy and the Chosen Children find themselves falling into nowhere, followed by their Digimon...
Once they stop falling, Koushirou opens up his laptop and establishes communication with Gennai, who tells them that they still haven't defeated the one behind all of the darkness in the Digital World: a Digimon who had emerged from the Wall of Fire and had never been mentioned up until now.
Gennai explains a bunch of plot threads that won't be mentioned again: long ago, a dark Digimon emerged from the Wall of Fire, warped the space-time of the Digital World, and threatened to destroy it until a group of five Chosen Children, predecessors to the current Chosen, sealed it. Before fizzling out, Gennai tells them that while the darkness surrounding them is the Digimon's existence, it also has a physical form, and wishes them luck in fighting it.
Said physical form reveals itself as a twisted, mutated, geometrical formation: Apocalymon. In the human world, the kids' parents witness the appearance of Apocalymon and their children preparing to fight it...
Apocalymon reveals itself to be a Fusion Dance Hive Mind of all of the Digimon who had died in the process of evolving, and when Koushirou explains that such a thing is inevitable due to Digimon evolution, much like Darwinian evolution, being based on those who are able to adapt to the environment, Apocalymon lashes out at him, telling the children that he is filled with hatred and resentment due to being composed of ones who have cursed their fates. Telling the Chosen that he hates them for being able to enjoy their lives happily, he attacks them, asserting that the Digimon who had died like this only wanted to be happy and live and that they deserved none of this, and thus want to Take Over the World and make it "theirs".
Apocalymon begins to use attacks of Digimon that they'd defeated against them, and the Chosen realize that he's effectively pulling a villainous All Your Colors Combined against them. Apocalymon declares that he'll make them feel the pain that the Digimon felt when they failed to evolve, devolves all of the Chosen's Digimon, and destroys the Crests and Tags. Devoid of their Transformation Trinkets, the Digimon are unable to evolve, and finally transforms the Chosen and their Digimon into basic data, causing them to dissolve away.
As they drift through the void of the world of data, the kids wonder if they're done for good, but their Digimon urge them to keep fighting and to never give up. After we're treated to a Clip Show (set to a slow piano rendition of the theme tune "Butter-Fly") of how all of the Chosen and their Digimon became stronger through their experiences with each other. Armed with this knowledge, and the moral support of the humans all around Earth, the kids resolve to keep pushing on and the symbols of the Crests begin to glow in their chests, the power of the Crests being drawn not from the physical versions but from the virtues in their hearts.
The power of the Crests restores the super-evolutions of the Digimon and the warp-evolutions of WarGreymon and MetalGarurumon. With that, the kids re-form in front of Apocalymon, ready to take him on.
- Big "WHAT?!": The English dub has Apocalymon say this when the Digi-Destined escape the Data World and reform in front of him for the final battle.
- Giant Space Flea from Nowhere: Apocalymon appears with little to no foreshadowing as the series' biggest, baddest villain, apparently having been behind the rise of the Dark Masters all along.
- Voice of the Legion: Apocalymon uses wareware, "we", to refer to himself in the Japanese version, as he's made up of a bunch of Digimon who had failed to evolve. This is removed in the American dub, where he uses the singular "I".