During World War II, Peter, Susan, Edmund and Lucy Pevensie are evacuated from London, little dreaming of the magical adventures that lie ahead. In the fantasy realm of Narnia, the children team up with a wise lion named Aslan, among other creatures, to battle the White Witch, who has turned the once beautiful land into frost.

Prince Caspian of Narnia wonders and dreams about the old days when animals talked, and there were mythical creatures and four rulers in Caer Paravel. But his uncle and aunt don't like to hear him thinking of such things, and plan to murder him and take his throne. Caspian's tutor Dr Cornelius manages to save him, and not only teach him about the old ways, but bring him into and introduce him to the real Narnia. But Caspian's plight is desperate, and he must use the legendary horn to call help from another world: Peter, Susan, Edmund, and Lucy. Lucy and Edmund are sent back to Narnia, along with their cousin Eustace, to assist Caspian on a voyage. Along their journey the children battle dragons and sea serpents, and sail across a golden lake to reach the edge of the world.

Shipped off to a miserable school, Eustace finds companionship in Jill Pole. Running from bullies, the two hide in a garden shed that magically transports them into the magical world of Narnia, where they're entrusted with a task by Aslan: to rescue the king's stolen son, Prince Rilian. Together, with Puddleglum the Marshwiggle, Eustace and Jill must travel north across the mountains, dodge giants, and journey down into the earth itself to rescue Rilian from the mysterious evil that holds him bound there.