Comanche moon : a novel
(Book)

In the waning days of the Old West, many of the great Comanche warriors are old, and their sons would rather use guns than arrows. As Texas Rangers Gus McCrae and Woodrow Call ride out to protect the frontier, they are led by the eccentric Captain Inish Scull, who sits astride a massive stallion Indians call the Buffalo Horse. When a scheming Comanche steals this great beast, it sparks a chase that will lead the Captain into the clutches of a sadistic Mexican warlord -- and Gus and Call into a legendary rescue

980,Lexile.