Harshly treated, Shasta believes that Arsheesh is his father until he overhears the fisherman negotiating to sell him as a slave to a Tarkaan (a Calormene nobleman).
They make their way to Tashbaan, Calormen's capital city, where Shasta is mistaken by a visiting Narnian party for Prince Corin of Archenland, whom he strongly resembles.
Riding with the Archenlanders, he becomes lost in dense fog, but is then guided by the great lion Aslan through a mountain pass into Narnia, where his warning musters a force of Narnians to come to the aid of their allies.
Shasta then discovers who he really is: Prince Cor of Archenland, elder son of King Lune, Corin's twin brother, and heir apparent to the throne.
When he was a baby, a prophecy predicted that he would save Archenland from a great danger, leading domestic enemies of King Lune to kidnap him.
Cor and Aravis eventually marry, and their son Ram the Great becomes (we are told) the greatest king of Archenland.