Former member of the Bill Williamson gang of outlaws, John Marston is forced to hunt down his old partner-in-crime to settle an old score, or more harm will come to his own family. Driven further into the American Southwest, Marston soon finds that Williams has crossed into Mexican territory hotly disputed by the Mexican Army and insurgent rebels.Former member of the Bill Williamson gang of outlaws, John Marston is forced to hunt down his old partner-in-crime to settle an old score, or more harm will come to his own family. Driven further into the American Southwest, Marston soon finds that Williams has crossed into Mexican territory hotly disputed by the Mexican Army and insurgent rebels. At every turn, he has to decide who to side with, outlaws, lawmen, rebels, or innocents in the crossfire.