Simplify the following text for a Grade 4 native English-speaking person.
Original: Prince Caspian , later to become King Caspian X of Narnia , Lord of Cair Paravel and Emperor of The Lone Islands , also called `` Caspian the Seafarer '' and `` Caspian the Navigator '' , is the title character of the second book in the series , first introduced as the young nephew of , and heir to King Miraz of Narnia . Prince Caspian : The Return to Narnia is set 1300 years after the rule of High King Peter and his siblings when Old Narnians have been driven into hiding by Caspian 's ancestors the Telmarines .
Simplified: They travel on a ship with Caspian , now King of Narnia .