Agumon, Gaomon and Lalamon decide to go to the Digital World and wind up in an area resembling a theme park full of many other Digimon, including Calumon who decides to follow them. After hopping on a vehicle resembling a roller coaster cart, Agumon's horrible driving skills lead them throughout adjacent including off of a cliff, through caverns, a volcano, an icy crag, a haunted area, and landing in something similar to the Dark Area. They find that the data is breaking down and being absorbed by Armageddemon. Agumon and Gaomon evolve to GeoGreymon and Gaogamon in order to fight it, and Calumon uses its powers to negate the black hole underneath it. After Armageddemon is defeated, the Kuramon that made up its body return the areas back to normal.
(Numbers indicate order of appearance. Bolded characters are fought by the protagonist(s), and italicized characters feature non-explicitly, e.g. voice, silhouette, image.)