When Tai and Matt argue about climbing Infinity Mountain to get a better view of their surrounding, Joe and Gomamon decide to climb the mountain by themselves. While on the mountain, they are attacked by Unimon. Tai and Sora come to their rescue, and Gomamon Digivolves into Ikkakumon to save Joe and destroy the Black Gear controlling Unimon. The three children soon reach the peak and learn they are on an island.