The Nine (American Post-Civil War Westerns) by William Black

The Nine. Scattered across the Indian Territory. With the sting of his friend’s death still fresh, US Marshal Caleb hunts down the nine outlaws, one by one. But after taking down the first outlaw, Caleb discovers an unexpected victim. Runaway bride Hannah. With little more than a Colt between the pair, Caleb and Hannah’s plans start to intertwine.