Ten years before Sora ever held the Keyblade in his hands, mysterious monsters called "Unversed" attacked the Realm of Light. Three young Keyblade wielders named Terra, Ventus, and Aqua, all three aspiring to be Keyblade Masters, are sent to neutralized this threat. But does the disappearance of a Keyblade Master named Xehanort has anything to do with it? What is with this masked boy they encounter during their journey? And can their friendship survives to the end?