The council of the frontier town of Sundown meets to discuss the wave of crime that has terrorized the area since the announcement of the coming of the telegraph. Pop Sawyer, the blacksmith, promises changes for the better with the arrival of Johnny Barrett, the son of Sundown's former sheriff, who was killed ten years before. On the Cheyenne stage to Sundown, Johnny meets Archie McDonald, the telegraph company representative, who, as an Easterner, anticipates the wildness of the West. When the coach is attacked by bandits, Johnny refuses to use guns to fight them off, but his quick thinking saves the stage and prompts Archie to admiringly dub him "Jesse James." Upon arriving in Sundown, Johnny is immediately threatened by the town thugs, but refuses to respond with violence, causing the townspeople to have misgivings about him. Pop tries to convince Johnny to behave more like his tough father, but Johnny tells him he does not like "gun-law," as his father was shot in the back. Shaken by the threats, Archie plans to recommend the telegraph company set up their new line through Fargo rather than Sundown. Pop protests, believing that the telegraph would lead to the establishment of an army outpost which would rid the area of crime and save Sundown. Later that night, when Johnny and Archie are attacked in their hotel room, Archie gets angry and decides that Pop's idea is correct. He promises to bring the telegraph equipment to Sundown and not report the assaults to the company. Unknown to everyone in Sundown, local businessman Amos Martin, with the help of Sam Carson and the corrupt sheriff, has been orchestrating the menace to the telegraph because he has large financial holdings in Fargo. Under Martin's orders, Carson sends his men to intercept Archie and steal the equipment before it reaches Sundown. When Archie stumbles into town seriously injured, Johnny and Pop seek out his attackers and the missing materials. Upon discovering the hideout with the equipment, Johnny and Pop tangle with Carson's men, one of whom is killed by his own gun in a struggle with Johnny. They return the materials to Sundown, but a recovering Archie reluctantly declares he must call a halt to the construction of the line, as he cannot in good conscience risk the lives of company men. When Johnny tells him the townsfolk will erect the telegraph line, sparing the company, Archie agrees. Martin meets with Carson and the sheriff, and tells them to let the installation of the line proceed, as he plans to sabotage the entire system at the opening ceremonies in front of the company president, ensuring that Fargo will then receive the line. Martin and Carson's men set dynamite charges along the line, which will be triggered by the initial telegraph signal. When Johnny and Pop grow suspicious of Martin's offer to help lay the line, the sheriff arrests them for the death of Carson's thug. Johnny and Pop stage a ruse to get out of jail and then discover the dynamite. Johnny finally straps on guns as they rush to reach the opening of the line and is just in time to prevent the company president from pressing the signal. When Martin attempts to reach the signal instead, Johnny shoots his hand. Martin, Carson and the sheriff are arrested and the dynamite is removed from the line, allowing the hookup to be completed safely. Sundown's first message is from Archie, who offers Johnny a job managing the telegraph office.