U.S. Marshal Ezra Macahan picks the wrong time to visit his kid brother, Joshua, a cavalry soldier stationed at Camp Furlong, New Mexico. That night Pancho Villa and his revolutionary forces raid the nearby town of Columbus. The Villistas are defeated but during the battle, one of Villa's ruthless commanders, Manuel "Scar" Acosta, kidnaps Joshua's son, Daniel, and flees to his mountain hideout.
Ezra and Joshua are about to pursue him, when they discover that their brother, Lt. Zachary, a recent deserter, was captured while riding with Villistas and now faces execution for treason. Ezra and Joshua visit Zach in jail. He agrees to lead them to Scar's hideout, but only if they break him out. Ezra refuses, forcing Zach to escape on his own. The brothers ride after Scar, accompanied by Joshua's fiery Mexican wife, Celia, who hopes to persuade her people to betray Scar's whereabouts.
But unpleasant surprises await them in Mexico, surprises that begin with Zach suddenly showing up and agreeing to lead them to Scar's heavily-guarded hideout and culminate in his violent death and a shocking revelation by Scar that threatens to destroy Joshua's love for Celia. Can Marshal Macahan overcome these adversities, rescue Daniel and save his brother's once-blissful marriage or will they all be killed by Scar?