Peter and his siblings are just hanging out at the train station when they are pulled into another world. You'd think they'd be use to it by now, but nope. Still freaky.
They explore the world to discover a bunch of ruins.
After sleuthing out a few clues, Peter realizes they are at Cair Paravel, their one time Narnian home.
Finding the treasure chamber, Peter reunites with his old shield and sword, named Bash and Slash (okay, fine, they don't have names; those are just the names we came up with for them).
The next morning, the Pevensies rescue a dwarf from some soldiers. The dwarf is thankful for the assist and also that they aren't ghosts (two good things to be thankful for).
The dwarf, one Trumpkin by name, tells them the story of Prince Caspian and his rebellion.
Peter and his Pevensie clan agree to help this Prince Caspian when they realize it was his blowing of Susan's horn that brought them here.
They travel to meet Caspian and get lost just a wee-bit. Eventually, they reunite with Aslan and find their way.
At Caspian's camp, Peter helps the Prince duke it out with some wicked fantasy creatures.
He then challenges Miraz to a duel, figuring it's the best chance they have for victory.
During the duel, Peter gains the upper-hand before Miraz is killed by his own lordly peeps.
In the ensuing battle, Peter leads the Old Narnians to victory.
After knighting Caspian, Peter and his sibs return to their own world. Although Peter can never return to Narnia, he now gets to go to school, so that's… wow. That's actually a pretty weak trade off, huh?