Complex sentence: Narnia is now ruled by King Miraz and his wife Queen Prunaprismia, but the rightful king is Miraz's young nephew, Prince Caspian, who has gained the support of the Old Narnians.
Split into simpler sentences: Narnia is now ruled by King Miraz and his wife Queen Prunaprismia. But the rightful king is Miraz's young nephew, Prince Caspian, who has gained the support of the Old Narnians.