A deputy marshall (Smeed) kills a ranch hand and steals a sack of gold. He claims it was a fair fight but the marshal of Arizona's Southern Territory (Forrester) has his doubts. Unknown to Smeed, there was a witness to the murder (Nachez). While the investigation unfolds, Smeed tries to cover up the evidence and eliminate people who can implicate him.
Another deputy (Gentry), who has always admired Smeed, defends him to his girlfriend (Alvarado) but is astonished when Alvarado translates the written eyewitness account (from the Spanish) by Nachez. Smeed kidnaps Nachez, taking him to a mine, where he kills him and hides the body. Gentry shows up at the mine but is over-powered by Smeed, tied up, and left to be buried in a cave-in caused by Smeed setting a charge.
The marshal arrives with his posse and hunts down Smeed inside the mine, using an alternate entry. In the meantime, Gentry, who survives the cave-in, unties himself and joins the hunt. The posse corners Smeed, who draws first, and is killed by Gentry. In the closing scene, Gentry (with his new bride, Alvarado), is presented with a new badge by Forrester and congratulated for being appointed to the position of marshal of Arizona's Northern Territory.
