As T.K. and Patamon play with the baby Digimon in Primary Village, Leomon arrives to attack them. The two go and hide but they run into Ogremon who has kidnapped a Poyomon. Leomon then catches up to them. As he is about to kill T.K., Matt, Garurumon, Tai and Greymon show up to save them. As the four champion level Digimon are fighting, more Black Gears embed themselves into Leomon who becomes huge and more evil and powerful. He easily defeats Garurumon and Greymon. Patamon's attacks do nothing against him. Just then, Izzy, Kabuterimon, Mimi and Togemon come. Izzy and Mimi inform the others that their Digivices have the power to destroy Black Gears. Tai and Matt shine them on Leomon who turns back to normal while Kabuterimon drives of Ogremon. Leomon tells the kids that legends say that a group of children called the DigiDestined will come to the Digital World and save it from darkness. He knows it is them because they can Digivolve their partners. Izzy predicts that after saving the Digital World they will be able to go home. The group then sets of to defeat Devimon. However, Devimon is not worried as he sends out more Black Gears. Sora, Birdramon, Joe and Ikkakumon see them on there way to Infinity Mountain.
Tai's group have reached the peak of the mountain when suddenly Devimon appears. Right after, Sora's group does too. The Digimon with the ability to all digivolve and the six of them along with Leomon begin to fight Devimon but they have no effect on the powerful Digimon. T.K. and Patamon stand by helplessly as Devimon is about to get them. The others try to save them but can't. As Devimon grabs the two, a light starts shining from his hand. Patamon has digivolved to Angemon!
Devimon is still not worried but Angemon says that he will destroy Devimon and bring peace. He gathers energy from all of the digivices which causes everyone to de-digivolve except for him who is now more powerful. He sends a strong blast right through the evil Digimon. Devimon is destroyed but he is telling Angemon that there will be more evil and he has used up all of his energy too. For that reason he is also dying. As T.K. cries, Angemon uses the last of his energy to tell him that he will come back. His feathers then come together to form a Digi-Egg which T.K. hugs and vows to take care of as the others assure him that it is Patamon.
The island then starts to reform as the darkness has been defeated. As the kids wonder why they are not going home, they realize there must be more evil they have to fight. Then a hologram of an old man appears he tells them he is pleased with them, leaving everyone wondering who he is.