Lucy and Edmund, accompanied by their peevish cousin Eustace, sail to the land of Narnia where Eustace is temporarily transformed into a green dragon because of his selfish behavior and skepticism.

A king and some unexpected companions embark on a voyage that will take them beyond all known lands. As they sail farther and farther from charted waters, they discover that their quest is more than they imagined and that the world's end is only the beginning.