During an eclipse night in the magical land of Narnia, at the Telmarine castle, Lady Prunaprismia
gives birth to a baby son. General Glozelle brings the news to the lady's husband Lord Miraz,
who immediately reminds Glozelle of his orders: he must find Prince Caspian the tenth, who is the
rightful heir to the throne, and kill him. Doctor Cornelius overhears this and rushes to wake up
Caspian to hide him in his armoire right before Glozelle arrives with his men and they attack
an empty bed. Afterward Cornelius helps Caspian get ready to escape and gives him an ivory horn,
which must only be blown in an hour of dire need. Caspian leaves the palace after knocking down
a few guards, but soon more men begin following him. Knowing the guards are scared of the woods,
Caspian enters the Shuddering Woods to hide there only to end up falling off his horse
when he's accidentally hit by a tree. Then Caspian is found by Trumpkin, Nikabrik, and Trufflehunter,
who immediately notice the guards coming after him. Trumpkin goes out to meet them and tells
Nikabrik to take care of Caspian, which makes the boy assume the worst. Caspian decides to blow the
horn, only for Nikabrik to knock him out for it. Meanwhile in London, sisters Susan and Lucy are
entering the Strand Underground station, where their brother Peter has gotten into another
pointless fight that soon their brother Edmund joins as backup. The fight ends when two guards
arrive and everyone scatters to avoid trouble. The siblings sit together and Peter complains about
being treated as kids when a year ago they've been in Narnia serving as kings, but Susan reminds him
they must accept their life here now. Suddenly Lucy cries out because something pinched her, and
the boys suspect it's each other, but Lucy quickly realizes something magical is going on. Susan says
they should hold hands and when the train passes by, the walls around them dissolve until the group
finds itself in a cavern near a beautiful beach. The siblings rush to play in the water, and Peter
points out they must be back in Narnia, but Edmund doesn't recall Narnia having ruins in it. The
group goes to investigate the ruins of a castle nearby and they're devastated to realize this is
Cair Paravel, the place where they once reigned. Meanwhile Glozelle and his men return to the
castle with a captured Trumpkin, which is perfect for Miraz's plan. Soon a council session begins
because the lords, including Sopespian, want to discuss the fact they don't trust Miraz, since
it's very suspicious that Caspian disappeared the same night Miraz had a baby. Miraz responds
by saying Caspian was abducted by Narnians, and as proof, Glozelle brings a gagged Trumpkin. Then
Miraz explains that Narnians aren't as extinct as they thought and that they’ve breeding steadily
while waiting for the right moment to conquer Telmar. He also swears he'll find Caspian and
finish what their ancestors began. Back at Cair Paravel, Edmund finds signs of barrage, meaning
the castle was invaded a long time ago. While time on Earth had only been a year, here a whole
century has passed. The siblings keep looking around and discover the royal treasure room is
still intact, so they use Edmund's torch to find their old royal clothing and weapons. However,
Susan's horn is missing. Lucy also gets sad because she realizes all the friends they had here
are now dead. Once they're properly armed, the siblings go looking for answers. At that moment,
they discover a boat rowed by two Telmarine soldiers, who grab Trumpkin with the intent
of drowning him. They're suddenly interrupted by an arrow that lands on the boat shot by Susan,
who demands the dwarf be freed. The soldiers throw the dwarf into the water anyway, and while Peter
and Edmund rush to save him, Susan shoots one of the soldiers, which scares the other into running
away. Trumpkin isn't happy to be saved by humans, but he quickly changes his mind when he realizes
these four are the Kings and Queens of old. Part of him is still afraid this may be a trap though,
so Edmund accepts to have a quick spar to prove their identities. Since he hasn't done this in
a while, Edmund has some trouble at first, but soon his body remembers and successfully disarms
Trumpkin. The dwarf now believes them and thinks Caspian blowing the horn brought them here. In the
Shuddering Woods, Caspian finally wakes up and hears Nikabrik and Trufflehunter discuss what
to do with him. Still thinking the worst, Caspian tries to fight Nikabrik, only for Trufflehunter to
cut in and ask who he is. Caspian tells them his story and tries to leave to escape from his uncle,
only for Trufflehunter to stop him because the horn's a sign Caspian is supposed to save them.
At the castle, Miraz confronts Cornelius with the arrow they recovered from his fallen soldier and
asks about the horn. Cornelius explains the horn could summon the Four Kings and Queens, and then
Miraz orders his arrest for teaching Caspian about old myths. Sopespian notices all this
and tries to tell Glozelle he should reconsider whom he trusts, but Miraz interrupts them to send
Glozelle and his men to Beruna so they can capture Caspian before the Narnians do. In the meantime,
Trumpkin and the siblings row upriver while the dwarf explains that Aslan abandoned Narnia when
the siblings left, that's why the Telmarines were able to invade. Since then, the trees and many of
the talking beasts of Narnia don't talk anymore. When they make it to shore, Lucy sees a bear and
tries to befriend it, but the bear is savage and attacks her. Trumpkin immediately kills it and
reminds the kids that things in Narnian are darker now. In the shuddering woods, Caspian, Nikabrik,
and Trufflehunter go looking for more Narnians. When Trufflehunter smells the Telmarine search
party, the trio immediately runs away while the Telmarines chase after them. They manage to hit
Trufflehunter, but suddenly, a mysterious tiny creature begins attacking the soldiers,
killing them all in a matter of minutes with precise and deadly skill. Then the creature comes
forward and reveals to be a mouse name Reepicheep, who notices Caspian is also a Telmarine and
threatens to kill him. Trufflehunter immediately comes in his defense, explaining Caspian had been
the one to blow the horn. At that moment a party of centaurs arrive and join them because they've
also heard the horn. In a different part of the forest, Peter insists on taking the party
along a pathway that Trumpkin's sure doesn't exist anymore, it turns out the river eroded a
canyon where the crossing once was. Suddenly Lucy notices something across the canyon and is shocked
to see Aslan, the pseudo-god of Narnia, but for some reason the others don't see him too. Nobody
believes Lucy except Edmund, who has already learned his lesson last time. In the evening,
Caspian finds himself surrounded by a bunch of angry Narnians who don't know if trusting him or
not. The Telmarines are usually cruel to Narnians, but Caspian did blow the horn. An argument that
involves lots of screaming and accusations ensues, and Caspian finally gets them to calm
down by pointing out that he's the rightful king, so he can swear to bring peace between Telmarines
and Narnians. Glenstorm the centaur explains he's read the astronomical conjunction and this
is the right time for an alliance, and Caspian is finally accepted by everyone as their new leader.
Back to the siblings, they travel to Beruna and discover the area is occupied by Glozelle's men,
who are building a bridge and huge trebuchets by cutting down lots of trees. This path is too
dangerous to keep going, so the group returns to the spot where Lucy saw Aslan earlier. When
the others tease her for her vision, Lucy gets annoyed by their lack of trust and accidentally
falls through a layer of loose ground, only to discover this is a ledge they can take to
cross the river. Later at night, Susan wonders why only Lucy can see Aslan and admits she had
gotten used to living in England again, so having been dragged back to Narnia has been difficult,
especially because it can't be permanent. In the morning, Lucy finds some magic leaves and flowers
and follows them to finally find Aslan, who tells her "things never happen in the same way twice".
Then Lucy wakes up for real and tries looking for Aslan again. However she's stopped by Peter,
who has been stalking a mysterious figure that turns out to be an armed minotaur. Peter then
comes closer to investigate, only to be attacked by Caspian, which triggers a fierce sword fight.
After they exchange a few blows, Lucy asks them to stop as she notices this guy must be a friend
because he's surrounded by Narnians. Once the siblings realize Caspian is the prince-in-exile,
everyone does the proper introductions, and the Narnians are happy to have their Kings and Queens
back. Accepting to work together, their first step is to move to find some fort where they can
be safe to plan and prepare for battle. Caspian takes them to Aslan's How, and after an honorable
welcome from the centaurs, he shows them that this stronghold was built atop the table where Aslan
had died for Edmund's sins. Next, Reepicheep and his band of mice approach the bridge site
to steal weapons and armor, only leaving behind a message saying "you were right to fear the woods,
X". That X stands for Caspian the Tenth. Miraz discovers this and orders Glozelle to kill the
guards that failed to protect their weapons; he also announces that Caspian has obviously
turned renegade, so they need a new king. At Aslan's How, a faun sentry sees a Telmarine
scout at the edge of the woods. The war council gathers and Lucy says she wants to wait for Aslan,
but Peter is sure the enemy knows about them now so they must attack the castle while the enemy
troops are at the bridge. Caspian thinks it's a bad idea because nobody has ever captured the
castle, but Peter doesn't want to stay because it's not really a safe fort, and Edmund points
out the enemy can just wait for them to die of hunger here. In the evening, the Narnians
proceed with their plan. An eagle drops Edmund on a castle tower, and after knocking out the guard,
he uses his torch to guide the other eagles who carry his siblings and Caspian. Reepicheep and
his mouse army enter through the sewers, and the rest of the army waits in the forest until the
kids can open the gate. The kids enter the castle through a window, and Caspian discovers Cornelius
was captured, so he rushes out to rescue him while promising to get to the gate in time. While the
mice beat up guards and even a cat, Caspian finds and rescues Cornelius, who explains it
was Miraz who killed his father. Furious, Caspian rushes to confront Miraz with his sword, causing
Prunaprismia to answer with her crossbow. Then Susan and Peter arrive to remind Caspian about the
gate, but the prince is obsessed with wanting the truth. Miraz admits he killed Caspian the Ninth,
and Prunaprismia doesn't recognize her husband anymore. Confused, Prunaprismia shoots her bow and
hurts Caspian, giving Miraz the chance to escape and call the guards. Meanwhile Edmund accidentally
drops his torch and it's caught by a guard, so he begins fighting the man for it. As Caspian,
Susan, and Peter reach the gate to finally open it, Edmund finally gets the torch back and sends
the signal to make their troops attack. A fierce battle begins between Narnians and Telmarines,
with lots of fighters falling on both sides. When Miraz orders his men to close the gate, a minotaur
rushes to keep it up and Peter orders the Narnians to fall back. A griffin rescues Edmund and most of
the Narnians escape on horses, but at that moment an archer kills the minotaur and the gate closes,
leaving half of the Narnians inside. Peter and the others can only watch helplessly how their
friends are killed before they run away and return to the How with defeat on their shoulders. Peter
and Caspian begin arguing over their plans and if Telmarines have a rightful place in Narnia
at all. The two of them almost start a duel, which is interrupted by the arrival of Trumpkin's body.
Lucy rushes to heal him up, but a mother centaur has a breakdown when she hears her children died
in battle. Later, Miraz crowns himself king and accepts troop pledges from his feudal lords.
Those troops are immediately sent to the bridge, which is finally finished. Meanwhile Nikabrik asks
Caspian to meet the power that once kept Aslan at bay, and introduces him to a werewolf and a
hag. These creatures swear they have a reserve of hate none can match and they can guarantee Miraz's
death. Then the hag proceeds to draw a magic circle, and with the help of a crystal scepter,
she summons an icy block that contains Jadis, the legendary White Witch. She needs a drop of
human blood to escape and promises to help them if they help her first, so the werewolf grabs a
hesitant Caspian while the hag gets blood from his hand. Suddenly Peter, Lucy, Edmund, and Trumpkin
arrive and begin to fight the creatures to stop them from bringing their old enemy back. A fierce
battle ensues, and Nikabrik gets very close to killing Lucy, but Trumpkin kills him first. Edmund
uses his skills to draw the werewolf away and proceeds to kill it with a single hit. Meanwhile
Peter pushes Caspian out of the magic circle and confronts Jadis, who begins using her charms to
convince him to join her. Suddenly the ice block shatters in million pieces, and Peter notices
Edmund used his sword to destroy it. Moments later, Miraz's troops arrive at the How. Peter
finally recognizes how wrong he was about doing this alone and tells Lucy and Susan to go deep
into the Shuddering Woods to look for Aslan, since he's their only hope. Before the girls leave for
the forest, Caspian tries to give Susan her horn, but she tells him to keep it because she may need
to call her again. Since Lucy doesn't understand romance yet, she doesn't get the conversation.
Then Caspian shares an idea with the boys to buy some time for their sisters: Miraz's weakness is
that as a king, he must satisfy the traditions and expectations of his people, meaning someone
should humiliate him in a duel. Edmund puts on his old royal armor before walking right into Miraz's
camp to deliver Peter's written message asking Miraz for a single combat. Miraz is hesitant, but
his lords manipulate him into accepting because they're secretly conspiring against him. Meanwhile
Susan and Lucy reach the middle of the woods, only to encounter a Telmarine patrol. Susan sends Lucy
away and begins fighting the men with her bow, managing to kill three Telmarines before they come
closer to kill her. Fortunately Caspian shows up just in time and rescues her, bringing her back to
the How. In the ruins outside the How, Peter and Miraz engage in a fierce fight that lasts forever
because they're both very talented swordsmen. Eventually Peter asks for a five-minute break,
and Miraz grants three. Susan arrives and informs them Lucy has made it through while
Miraz argues with Sopespian for not intervening in the fight to help him. It's illegal to do so,
but Sopespian refuses because of personal reasons, not because of the rules. When Peter and Miraz
restart their fight, they exchange a few blows and this time, Peter finally gets to defeat Miraz,
but instead of killing him, he gives his sword to Caspian, since this is his right. Caspian decides
to spare Miraz but will hand the sovereignty back to the Narnians. However Sopespian cuts in and
kills Miraz himself using the arrow of Susan's they retrieved from the soldier. Then Sopespian
says the Narnians shot the arrow and cries out treachery, causing the Telmarines to launch a full
attack on the How. The artillerymen make full use of their trebuchets, so the Narnians make
a special plan to counter-attack: they mine the ground under the horses' hooves to make them fall,
then Susan and her archers shoot a hail of arrows at the falling men. Glozelle guides
his cavalry into a charge, but Caspian together with Glenstorm and his own cavalry surprises the
enemy by charging them from behind. Sopespian responds by sending his own infantry and the
artillerymen manage to send a bunch of boulders to crash the gate of the How, which instantly seals
it. It seems the Narnians will be defeated soon. At that moment in the forest, Lucy is being chased
by Telmarine guards, but she's saved by the sudden arrival of Aslan. After scaring the guards away,
he awakes all the forest trees with a mighty roar. Back to the battlefield, Caspian falls
into a sinkhole and Glozelle approaches him to kill him, only to start hesitating. Before he
can make his choice, a tree root picks him up and knocks him out as the trees take over the field,
turning the tide in favor of the Narnians. A trebuchet manages to kill a tree with a rock, but
another tree extends a root and finally crushes the trebuchets. Then the siblings and Caspian
lead the counterattack, forcing Sopespian and his troops to take the bridge in order to escape. The
group goes after them, but Sopespian encounters Lucy and Aslan first and makes his soldiers attack
them. Aslan simply responds with another mighty roar and awakens the personification of the river,
who lifts the bridge and hits the troops with its water, drowning Sopespian in the process.
Afterward, the remaining Telmarines surrender to the Narnians. Aslan reunites with everyone
and accepts Caspian as the next king of Narnia. At that moment, the band of mice brings Reepicheep,
who has died in battle. However, Lucy uses her magic medicine and revives the little mouse,
who bows for Aslan before noticing he has lost his tail. Aslan teases him for it before restoring his
tail too. Afterward, Aslan takes Caspian and the siblings through Telmarines' capital, where the
citizens meet them with cheers and fireworks. When they make it to the castle, Caspian announces that
Narnia will be a Narnian-Telmarine federation, and any Telmarine that doesn't like that can
return to the land of their forefathers, which happens to be an island on Earth that contained
a portal to Narnia. Glozelle immediately accepts to come back and takes Prunaprismia and her son
with him. Aslan opens a portal for them, and they disappear after crossing it. Peter uses
the moment to point out Caspian must now take charge, meaning he and his siblings will take
the portal and return to their normal lives too. Unfortunately this means Peter and Susan won't
return to Narnia ever again because they're too old. After Peter gives Caspian his sword,
Susan takes a moment to say goodbye to Caspian, lamenting that a romance between them would've
never worked because she's thirteen hundred years older than him, but she does gift him a kiss. The
siblings step through the portal and magically find themselves back on the underground platform,
where they take the next train as Edmund complains he forgot his torch in Narnia.