While camping deep in the backwoods of Alabama a married couple, Dillon and Brenner Baker are out hiking when they stumble across an illegal drug and gun storage compound. Before they can flee the area the Cartel captures and tortures them. The Cartel makes two mistakes though, they kill Dillon and think they killed Brenner. Now, 1st Lieutenant Brenner Baker of the Army's 75th Ranger Division is on a one woman killing mission carving up everyone in her path until there's only one person standing, her. Brenner is, an Army of One.