A hit man turns against his former boss after witnessing a nuclear weapon being smuggled into the US.

Two Tejanos (Texas of Mexican descent) kill two white men in a small south Texas town in 1883. One witness and his little brother accompany a Texas ranger turned bounty hunter across the Nueces strip in pursuit of these fugitives.

U.S. marshal Britt MacMasters returns from a mission to find his father wounded and his son kidnapped by the outlaw Jed Blake. Hot on their trail, Britt forms a posse with a gunslinging deputy and a stoic Pawnee tracker. But Jed and Britt tread dangerously close to the Red Desert’s Sioux territory.