Day after day, Sora, Riku, and Kairi talk and dream of new places, new worlds beyond their islands. They ponder the usual questions that adolescents do-about the world outside, about their existence.

Little do they know a great destiny awaits them. One stormy night, a terrible darkness invades the Destiny Islands.

Thus does their journey begin...

Sora awakens in another world, in a place called Traverse Town. His hopes of seeing new worlds are realized, but his friends Riku and Kairi are nowhere in sight.

Meanwhile, Donald and Goofy have also arrived in Traverse Town. They have come from Disney Castle in search of a "key" and its owner. Their king, who has mysteriously disappeared, has left them a cryptic message:

"Now, there's somebody with a 'key'-the key to our survival... we need that key."

What is happening to this world?

The "somebody" mentioned by the missing king turns out to be Sora. To find Kairi and Riku, Sora joins Donald and Goofy and embarks on an epic journey.