Ricochet — Thom Nicholson

There's a $3,000 bounty on James Bennett's head, and Marty Keller intends to collect it. Deep in the Oklahoma badlands, Keller corners his quarry, pinning him down with warning shots...until one ricocheting bullet strikes Bennett in the back, mortally wounding him.
 
Keller returns to Fort Wayne to collect his reward, only to be branded a back shooter by the townsfolk. Then, to his surprise, Bennett's widow pleads with him to escort her and her young son to their new home in Wyoming Territory. And as he sets out to lead them across countless miles of mountains and prairies, Keller is determined to protect his charges from any danger that may befall them -- both natural and human.