The Marshal’s Gambit (American Post-Civil War Westerns) by William Black

Payne Conway didn’t plan on staying in Arizona – until the outlaws start falling to his .44. As town marshal, Payne clashes with ruthless businessman Sam and his Hand Gang, after he tosses one of Sam’s outlaws in jail. Teaming with Clementine Boyd, whose sister has gone missing, they face the desperados in a fight to save the town, or die trying.