Sora, Donald, and Goofy have defeated Ansem and restored the world. But beyond the dark door—a door that had to be closed—Riku and King Mickey remain. And so the trio sets off again on a journey to find Riku and the king. As they progress through Castle Oblivion and encounter agents from the mysterious Organization XIII along the way, Sora and his friends begin to lose their memories. What does it mean to hold something dear? And in the end, what path will Sora choose?