Lawlessness casts a dark shadow over Muskogee, Oklahoma in 1909 as it adjusts to statehood. Bandits and businessmen alike struggle to adapt to life in the former Indian Territory and the Nations. Andrew J. McGrath returns from the Spanish-American War with a hidden case of shell shock. He resigns his commission after an unspeakable tragedy and turns to gambling. Ten years later, he is weary of danger from gamblers, corrupt officials, and bankers.

A drunk cowboy and two friends attack McGrath after an all-night card game. He kills them with help from Bass Reeves, one of the first black US Marshals west of the Mississippi.

McGrath joins the fight to rid the city of miscreants and malefactors, including the deputy chief of police.