Wesley Case is a former soldier and son of a Canadian lumber baron who sets out into the untamed borderlands between Canada and the United States to escape a dark secret from his past. He settles in Montana where he hopes to buy a cattle ranch, and where he begins work as a liaison between the American and Canadian militaries in an effort to contain the Native Americans' unresolved anger in the wake of the Civil War. Amidst the brutal violence that erupts between the Sioux warriors and U.S. forces, Case's plan for a quiet ranch life is further compromised by an unexpected dilemma: he falls in love with the beautiful, outspoken, and recently widowed Ada Tarr. It's a budding romance that soon inflames the jealousy of Ada's quiet and deeply disturbed admirer, Michael Dunne. When the American government unleashes its final assault on the Indians, Dunne commences his own vicious plan for vengeance in one last feverish attempt to claim Ada as his own.