The Chronicles of Narnia
The Horse and His Boy:
This book is one of seven in C.S. Lewis' famous, 'The Chronicles of Narnia'. It is about a young boy, Shasta, who lives with a fisherman in Calormene (you have to read the books to understand). He doesn't look anything like the old man and soon finds he was adopted. He then meets Bree, a talking horse captured from Narnia when he was a foal, and together they set off towards Shasta's birth place, Narnia.
This book is very exciting and well written. But I recommend reading the other books first in order to fully understand this one.