Big city cop Joe Case arrives in a small town on the Mexican border to visit his former police partner, Dave Buchanan, now a sheriff’s deputy. After getting settled, Joe joins Dave and his wife, Jess, on a horseback ride through the desert wilderness. Jess Buchanan’s Uncle Warner, whom she describes as “the best tracker in the whole country,” accompanies them. As they approach a canyon, Warner advises that the horse Joe is riding might not be able to ride fast enough through the canyon, so Joe turns back while the others continue. Meanwhile, a group of illegal aliens sneaks across the border from Mexico and are immediately arrested by sheriff’s deputies. However, one young woman in the group is taken away, held hostage in a barn, and raped. When the young woman escapes, her captors give chase. As she dashes through the wilderness, she runs into Joe on horseback, returning to the Buchanan house. Scared by her sudden appearance, Joe’s horse throws him to the ground. Joe goes after the woman, but she is recaptured. Hiding in the brush, Joe watches as the men drag her away. Moments later, when she escapes again, Jake Wheeler, the leader of the group, shoots her in the back, killing her. The next day, Dave Buchanan takes Joe to tell Sheriff Lawrence Mitchell what he saw. As he makes his report, Joe is stunned to see that Jake Wheeler is a deputy sheriff. As soon as they leave, Joe tells Dave that Wheeler is the man who shot the girl. Meanwhile, Wheeler has his men dig up the body, and by the time the sheriff’s cars arrive at the murder spot, there is nothing to find. Joe Case makes a veiled accusation toward Wheeler, who punches him in the face. Wheeler advises Dave, “You better cool your boy down.” After they leave, Joe tells Dave he accused Wheeler to see what kind of reaction he would get. Later, Sheriff Mitchell tells Dave that he believes his deputy and advises him to keep Joe away from Wheeler. When Joe returns to the murder spot, he finds a sheriff’s deputy napping in his car rather than guarding the area. Soon, Dave arrives with Uncle Warner, who examines the area by following footprints and other telltale signs. Warner determines where the woman’s body was buried and also points out the spot where she fell upon being shot. They find the trail where she ran and the barn where she was being held. Dave arrests a man inside the barn, but when they leave, Wheeler, who has been observing from afar, shoots and kills the man with a high-powered rifle. Joe, Dave and Warner dash back into the barn, but Wheeler keeps shooting. The three run out the back of the barn and find safety. At the morgue, the sheriff lies to Dave and Joe, saying that he knows where Wheeler was during the shooting and he is not responsible. However, he promises they will find out who shot at them. Joe comments to Dave that if the dead woman were white rather than Mexican, the deputies would be investigating the crime with more enthusiasm. Dave replies that if the woman were white, they would likely already know who she was. Meanwhile, Wheeler stops by a building and picks up an envelope full of cash. The next day while checking out a lead at a salvage yard, Joe Case recognizes one of the men from the shooting. Knowing he has been spotted, the man gets in his truck and drives away while Joe and Dave give chase in their truck. The man’s truck overturns and he starts running, with Joe and Dave following close behind. The man makes it to the border and crosses before Joe and Dave can capture him. Joe wants to follow him into Mexico, but Dave reminds him they do not have jurisdiction there. Back at the Buchanan home, Dave’s wife, Jess, is preparing dinner when Wheeler sneaks in. She holds a knife out to defend herself, but Wheeler turns the knife toward her. He tells Jess he can come in any time and take her, then leaves. Dave telephones the sheriff’s station, but Wheeler overhears the deputy taking the message. Wheeler goes home and stuffs cash into a duffle bag. His wife wants to go with him, but Wheeler leaves without her and goes to see the sheriff at home where he admits that he killed the woman. Wheeler comments that the sheriff knew what was happening all along, but wanted to get rich, so he looked the other way when illegal aliens paid money for help crossing the border, then were arrested on the American side. The sheriff advises Wheeler to take the money and run. Armed with shotguns, Joe and Dave go to a building, but are ambushed by Wheeler’s men. Many shots are fired and Dave is hit. Wheeler takes Dave’s shotgun and shoots him to death. In another part of the building, Joe Case is also shot and believed to be dead. Wheeler instructs his men to place Joe’s body beside Dave’s, then set the building on fire. However, as Joe is carried into the room, he stabs his captor in the back with a knife and escapes. Joe drives Dave’s truck back to the Buchanan house and Jess immediately realizes her husband is dead. Joe goes to the sheriff for information and reminds him that some of Wheeler’s men who killed Dave are sheriff’s deputies. The sheriff reluctantly tells him to go to the Cantina Paloma in Mexico and ask for a man named Romo. At the cantina, Joe approaches Romo, demanding to know Wheeler’s whereabouts. Romo pulls a knife on him, but Joe pulls a gun on him. Romo takes him to a spot in the desert where he finds Wheeler standing with a four other deputies. However, the deputies back away, leaving Joe and Wheeler to fight alone. Joe shoots Wheeler with his shotgun. Wheeler falls to the ground dead and Joe walks away.