The mining community of Lamplight, Colorado has been troubled for some time, as prospectors on their way to the Monarch Smelting Works have been consistently robbed of their gold and murdered. The plant superintendent, Lloyd Chapin, is worried, and the miners give Sheriff Bob Brewster only a few more days to catch the bandits before they will vote him out of office. Soon, Travis and Larkin, two miners who are secretly behind the crimes, falsely accuse newcomer Neal Wallace of their latest crime, the robbery and murder of miner Webb Hammond. They bring Neal into town, where he professes his innocence to Bob and is backed up by prospector Little Joe Smith. When Travis incites the miner mob to lynch Neal, Bob makes Little Joe a deputy and charges him with escorting Neal to Bob's ranch, where he will be safe. Once there, Neal tells Bob that he is the vice-president of Monarch, sent to Lamplight to investigate the killings, but when Neal looks for his identification papers he finds that the outlaws have framed him again, replacing his papers with stolen gold. Despite his inability to prove his identity, Neal is able to convince Bob that he may be telling the truth about himself and Travis. Janet Hammond, Webb's granddaughter, remains unconvinced of Neal's innocence, and Bob agrees to send a telegram to Monarch president Mr. Comstock asking him to confirm Neal's position. Certain that he will be unfairly tried for the murders, Neal escapes. After a pursuit, Bob is overpowered by Neal and agrees to allow Neal to investigate Travis. Soon, Neal comes to suspect that Chapin is Travis and Larkin's leader, and proves the connection to Bob when Chapin sends Neal down an unused road and the outlaws are waiting there to ambush him. Neal escapes, trapping one of the band, Charlie, who inadvertently reveals that he does indeed work for Chapin. As Bob and Neal go to Chapin's office to check his books, Janet receives a wire from Comstock that corroborates Neal's story. When she chases Bob to the plant, she is taken prisoner by Chapin and his gang just as Bob and Neal leave. While Chapin and his men begin to load their gold for a quick getaway, Mary Brewster, Bob's sister, tells Neal of the wire's arrival and Janet's disappearance. With the help of the miners, they manage to capture Chapin and his gang and save Janet after a fierce gunfight.
