The DigiDestined and their partners are wandering through a cold forest. They are discussing all of the fun things they could do in the snow when Joe tells them they need to be more serious and safe but everyone else laughs and thinks Joe should lighten up. They find themselves at a field covered with snow and try to decide between crossing it or climbing the nearby Infinity Mountain. Before a discussion is reached, the kids smell something and see steam. After following the steam, they find a bunch of pools filled with boiling water. There is also a refrigerator filled with nothing but eggs. Joe doesn't think they should eat them but everyone else is hungry and disagrees. As everyone enjoys their feast of eggs, they start to feel homesick. The kids feel better after talking about their favorite kinds of eggs but Joe just gets annoyed. Everyone thinks he is acting weird and should lighten up but Joe says he is just being careful because nobody else will and he needs to be the voice of reason.
Tai and Matt are fighting over whether or not to climb Infinity Mountain. Tai says it would give them a great view of the whole island but Matt says it would be too dangerous and they don't know what's up there. As Joe goes to break up the fight, they try to make him take sides. Unfortunately, he sees valid points in both of their arguments. The kids finally decide to go to bed and figure it out in the morning, but Joe is worried that he is not being responsible enough as the oldest to take care of everyone. In the middle of the night, he and Gomamon go off on their own to climb Infinity Mountain.
After getting halfway up the mountain, it starts to shake violently. Black Gears start to appear at the top of it. As Joe and Gomamon go to see where the gears are coming from, a Unimon flies over them. Gomamon is about to go over and talk to him when a gear comes from the sky and embeds itself into Unimon's back. He then starts to attack.
Meanwhile, Sora wakes up and finds that Joe is gone. She thinks he went up Infinity Mountain and wakes up everybody else. As Unimon is about to unleash an attack on Joe and Gomamon, Birdramon shows up with Sora, Tai and Agumon. Unimon defeats Birdramon so Agumon digivolves to Greymon, but he is defeated too. To protect his friends, Joe jumps onto Unimon's back to try to pull out the gear. He can't do it and he falls off. Just then, Gomamon digivolves to Ikkakumon and catches Joe. He is also able to destroy the gear. Joe, Tai, Sora, Gomamon, Agumon and Biyomon then make their way to the top of Infinity Mountain. Upon getting there, they see that beyond the island is nothing but water.