In Narnia, Caspian, a Telmarine Prince, flees his castle on horse after his aunt has a son, meaning that if his treacherous Uncle Miraz were to kill Caspian, he would be the sole heir to Caspian's rightful throne. Chased by several Telemarine soldiers, Caspian encounters two Narnian dwarves and a talking badger in the woods. One of the dwarves, Trumpkin, is captured by the soldiers, while the other dwarf, Nikabrik, and the badger, Trufflehunter, save Caspian.

In England, the four Pevensie children wait for subway train to arrive, one year having passed in their world since they first entered Narnia. Just as the train pulls into the station, the walls start sucking in, and the whole station tears apart to leave the Pevensies in Narnia. There, they discover Cair Paravel, their castle, has turned to ruins.

Meanwhile, Nikabrik and Trufflehunter lead Caspian to the Dancing Lawn, where all the old Narnians have assembled, including the swashbuckling mouse, Reepicheep, and a large number of centaurs and minotaurs. There, Caspian convinces them to help him win his throne back so that he can give them back their land.

The Pevensies save Trumpkin as they spot two Telmarine soldiers who are about to drown him in the ocean. After the dwarf realizes that the four of them are the kings and queens of old, they set off together. On the way, Lucy glimpses Aslan and tries to convince the others that she's seen him, but only Edmund believes her. After many twists and turns, they eventually encounter Caspian and his troops, who take them to Aslan's How, a huge underground temple built over the Stone Table. From there, Peter suggests that they attack the castle. Lucy suggests waiting for Aslan to give instructions, but Peter decides they've waited long enough for Aslan.

The Narnians succeed in raiding Miraz's castle, but finally seeing that if they keep fighting they will all be killed, Peter calls for a retreat. Peter, Edmund, Susan, Caspian, and half of the Narnians manage to escape, but the rest are caught by the falling gate and brutally slaughtered.

When they get back to Aslan's How, Nikabrik, along with a hag and a werewolf, draw Caspian aside and tell him that they can help him claim his throne. The hag uses black sorcery to summon the White Witch. From inside a wall of ice, the Witch tries to convince Caspian to offer her a drop of his blood in order to set her free. Peter and Edmund arrive and quickly decapacitate Nikabrik, the wolf, and the hag, and Edmund shatters the wall of ice before the Witch can completely materialize.

As Miraz and his army arrive at Aslan's How, Prince Caspian suggests that Peter and Miraz duel one-on-one under the condition of surrender, in order to buy Lucy and Susan more time to find Aslan. Miraz is forced to accept, as it would look cowardly to refuse to fight a boy half his age. Susan and Lucy, who are searching for Aslan in the woods, are chased by Telmarine soldiers along the way, and Susan sends Lucy off and remains behind to deal with the soldiers. She is soon rescued by Caspian, and the two of them return to the battlesite. Peter and Miraz battle, and Peter eventually is able to wound Miraz, but gives his sword to Caspian to finish him off. Caspian, who cannot bring himself to do it, lets Miraz keep his life, but says that he intends to give Narnia back to its people.

One of the Telmarine lords suddenly stabs and kills Miraz with a Narnian arrow and blames the Narnians for shooting Miraz. He calls the Telmarine army, which is waiting just outside the How, to advance so that they can obliterate the Narnians. The Telmarines unfurl nasty trebuchets which fire a continuous stream of boulders at the Narnian army. In an effort to fight back, the Narnians try several tactics, including destroying underground tunnels underneath the army, and sending gryphons overhead with archers in their claws. In one final hope, they charge head on with the Telmarines.

Lucy, meanwhile, has found Aslan in the woods; he awakens the trees that have been in a deep sleep. The whole forest begins to ripple with movement, and this energy travels back toward the battlefield. With the whole forest suddenly against them, the Telemarines retreat back to the bridge of Beruna, where Aslan summons the river god, who destroys the bridge and wipes out the majority of the Telmarine army; all of the surviving Telmarine soldiers are forced to surrender and hand over their weapons.

Before the Pevensies depart, Peter and Susan declare, much to Caspian, Edmund, and Lucy's dismay, that Aslan has told them they will never return to Narnia. Aslan explains that Susan and Peter have gained everything they could possibly gain from their experiences in Narnia and are no longer needed there. Susan and Caspian share a kiss, knowing they will never meet again. Finally, the Pevensies go back to England, leaving Caspian as King of Narnia. (less info)