St. Agnes’ Stand by Tom Eidson

Nat Swanson didn't expect his flight from Texas to California to be easy, not with the friends of the man he recently killed (in self-defense) on his trail. He certainly wasn't expecting, in the middle of the desert, to find three nuns and seven orphans holed up and surrounded by Apaches (who have already brutally murdered a nun), and then to be regarded as their savior.
Nat struggles between his conscience and his desire to escape alone, all the while devising a daring plan to get them all to safety.
With the gripping intensity of their plight and with a cast of memorable characters, including Sister St. Agnes, an indomitable nun who plays poker and smokes, and Nat, a loner who has responsibility and faith thrust upon him, St. Agnes' Stand is a Western to recommend, even to those who don't usually read them.