The third book in the Chronicles of Narnia takes place during the reign of King Peter (along with his brother and sisters), and the Pevensies appear in this book as their (semi-)adult selves. The titular boy is Shasta, who lives with a fisherman who he’s pretty sure isn’t his father, and who abuses him. Dad’s about to see Shasta to a traveling noble person, which Shasta overhears, and is of two minds about the situation. Shasta starts talking to the traveller’s horse, who (to his amazement) talks back. The horse and the boy decide to run away to Narnia, where the horse is from.
Whilst on the run, Shasta and Bree (the horse) run into a young girl also running away from home (to escape an arranged marriage to a gross old man) and her talking horse Hwin. They have adventures, escape various perils, and Shasta gets mistaken for some prince kid (hmmmm).
Calormene, the place Shasta and Aravis are trying to escape, appears to be a sort of Persian/Arabian sort of place, with viziers and the like. They see the Narnians and Archenlanders (northerners) as barbarians, but act more barbaric (of course). Queen Susan rejects the Calormene prince, who decides to invade. Shasta and Aravis try to save the day, and Shasta learns who he really is.
Aslan makes his usual god-like appearance, helping things along, and of course it all works out in the end. I liked this one, it has a sense of humor, especially with all the invented aphorisms that Lewis puts in the mouths of the Calormenes (although they might be a bit racist). It’s another quick and easy read, as enjoyable as Lewis’ other stories.