Sora, Donald, and Goofy arrive at the End of the World. While searching for Ansem, the trio refight many of the mighty Heartless they previously encountered. Eventually, the group arrives at the World Terminus, finding the collection of portals to be a prison for the worlds. Shortly thereafter, the group finds a door. A mysterious voice warns Sora to be careful, as no light exists beyond that door. The voice continues, telling Sora that despite the danger, Sora has the mightest weapon of all: his heart. As the voice finishes, claiming Sora is the one who will open the door to the light, the group opens the door.
Sora, Donald, and Goofy find themselves back at the Destiny Islands. While walking around, a new voice sounds, claiming that the islands will soon be devoured by darkness. The beautiful islands slowly degrade to a lone island, surrounded by a black ocean. Riku appears, standing on the edge of the main island. He comments how this island was nothing more than a prison to a heart seeking freedom. As Riku turns around, Ansem reveals himself, stating that Riku finally belongs to darkness. The island shifts again, continuing to fade to darkness.
As the islands are completely consumed, the trio is left floating in darkness. Ansem appears, claiming that this endless abyss holds the heart of all worlds, Kingdom Hearts, and prepares to fight the group.
(Numbers indicate order of appearance.)
Items of note
Kingdom Hearts references