When his adoptive father is bushwhacked and killed in Texas in 1861, Rusty Shannon rides to fort Belknap on the Brazos River and joins the Texas Rangers. Mike Shannon's death haunts him; he owed his life to Mike, who rescued him from a Comanche War party when he was a child, and rusty thinks he knows the killer's identity. With Texas now in the throes of secession, Union sympathizers are regarded as traitors and it is Rusty's fate to fall in love with the daughter of such a sympathizer and fall afoul of the zealots who want to hang all Unionists.