In 1861, Western Union engineer Edward Clayton (played by Dean Jagger) was seriously injured in an accident. He was discovered by Vance Shaw (played by Randolph Scott) as a fugitive who had escaped from a team. After his horse was injured, Shaw was forced to travel on foot. At first, he considered stealing Clayton's horse, but changed his mind and took this person with him, saving his life. After a period of recovery, Clayton returned to Omaha, Nebraska, with plans to build a telegraph line from Omaha to Salt Lake City, Utah. Faced with strong opposition from Confederate soldiers, Native Americans, and outlaws, Clayton received help from his sister Sue (played by Virginia Gilmore), foreman Pat Grogan (played by Mino Watson), and assistant Homer Kettle (played by Cher Wells). In order to get rid of his illegal past, Shaw went to the Western Union office in Creton to find an honest job and was hired as a scout by Grogan, who knew nothing about his past. Clayton recognized him among these people and allowed him to stay, despite his doubts. Clayton also hired Richard Blake (Robert Yang), an engineer who was educated in Harvard University, to help his father. Shaw and Blake were both attracted to Sue and competed to attract her attention, but their romantic competition was interrupted when the telegraph line began construction on July 4, 1861. After the line started working, one of the men was clearly killed by a group of mysterious cattle stealing Native Americans. Shaw did not believe that Indians should be blamed, so he rode out to investigate and followed the thief's trail to Jack Slade's camp. Jack Slade was his former friend and companion, and his gang disguised themselves as Indians to kill. Shaw left the gang after his last bank robbery. Slade revealed that they are working hard for the Southern Alliance to disrupt Western Union because they believe telegraph services will help Western Union. Xiao rode away and returned to the team. Shaw told Clayton that a large group of Dakota Native Americans had stolen the cattle and suggested that they simply change the herd and not risk fighting with the Native Americans. After a period of time, there was a standoff between the man working on the front line and a group of drunken Indians. When one of the Indians attempted to steal some equipment, nervous Black ignored Shaw's command to remain calm and fired at him. After the news arrived, the main camp was being attacked by other Native Americans, and Western Union soldiers rushed back to help defend. At the main camp, Slade's men once again disguised themselves as Native Americans and stole Western Union horses. When one of the injured Indians turned out to be white, the company discovered this scam. Clayton was forced to repurchase the stolen horse from Slade, and he began to suspect Shaw's involvement, especially when he admitted to knowing the gang. Soon, the US Army arrived and announced that the Native Americans were now refusing to allow telegraph lines to pass through their territory in response to Black's shooting of drunken Native Americans. Clayton, Shaw, and Black rode horses to persuade the leader of the spotted horse to allow them to build a route through Indian territory, even though the person Black injured was the son of the spotted horse. Crayton was finally able to persuade the Native Americans to allow them to pass, and work continued until the company approached Salt Lake City. After a while, Xiao received news that Jack Slade wanted to meet him. On the way to meet Slade, Shaw was captured and bound by Slade's men. Slade stated that his team will burn down the Western League camp and they do not want Shaw to intervene. After Slade and his men rode away, Shaw escaped the rope, but returned too late to stop the fire. He helped rescue some Western Union men from the flames and burned his hands during the process. After the fire, Clayton confronted Shaw and demanded an explanation, but Shaw did not disclose what he knew, so he was dismissed by Clayton. When Shaw left the camp, he told Blake that Slade was actually Shaw's brother. He, Shaw, would find Slade's gang and prevent them from interfering with the telegraph project. Xiao rode away and found Slade and his men in a nearby town. At the barber's shop, Xiao faced off with his brother, his gun hidden under the barber's bedsheet. Slade shot Shaw through the sheets. Shaw counterattacked despite his injuries, killing some gang members and then dying. Black arrived and continued to fight Slade, who had died from severe injuries. Not long after, the Western Union Line was completed and the workers celebrated. When Sue lamented Shaw's absence, Clayton told her that Shaw could hear.