The events in The Horse and His Boy take place during the era of Narnia's Golden Age, when Peter the High King and Queens Lucy and Susan and King Edmund rule Narnia. It provides the only good look at what the Pevensies were like as grownup rulers, and it offers the only good look at Calormen in "The Chronicles of Narnia."

In The Horse and His Boy, two talking horses, a slave boy, and a girl from the Calormene aristocracy flee through Calormen north to the Desert and beyond, in hopes of finding a place where there are no slaves, where talking horses may live without fear of discovery, and where a girl cannot be forced to marry against her will.