To prevent a three mile journey around the mountain the telegraph wires at the construction camp have been strung over the precipice from the station on the mountain top. The operator is discharged when the superintendent suspects him of treachery and Helen is transferred to the station. Later, after the former operator has enlisted the aid of crooked brokers to use his knowledge in ruining the value of the road's stock, he receives an opportunity to get revenge on the superintendent.
Through an accomplice the band of conspirators preying on railroads succeed in having the boxcar loaded with auto tires sidetracked at Lone Point instead of being taken on to its rightful destination. They are getting away with the valuable shipment when Helen takes a hand in the affair. While each of the trio carries a load of tires back to the autos which are in a sheltered spot, Helen hurriedly climbs the side of the boxcar and releasing the brakes the car, with its heavy load, starts down grade at great speed.
Red Stanley's band has successfully robbed the express car and the members are making good their escape when they come upon Helen and her girl chum riding in the woods. The girls are set upon but they succeed by desperate riding in making their escape temporarily and, when danger seems near again, are saved by the approaching railroad detectives searching for the Stanley band. A running fight results in the capture of one of the band, but Stanley and his chief aide escape. Under cover of darkness, as Helen is working alone in the desolate station, the two enter and bind and gag her.
"Red" Byrd and his aides succeed in learning that a large treasure is being shipped on a certain freight car under special guard. They overpower the relief operator at Helen's station and tamper with the signals so that the treasure train stops, while the crew runs ahead to investigate, leaving Spencer alone to guard the treasure.
Chilton, a crooked dealer in antiques, decides on a daring scheme to recoup his finances by defrauding the railroad. A car-load of cheap furniture is shipped with a valuation of $40,000 on it. Blanding, the tool of Chilton and his partner, awaits at Lone Point a telegram giving the number of the car.
Deering and his gang rifle the station safe and gain possession of some valuable gems; Helen seizes the package and throws it into the river. In order to recover the package, a human chain is formed by the railroad men, which Helen climbs down and attempts to catch the package with her feet. Meanwhile, Deering and his men have boarded a launch, and succeed in grabbing both Helen and the package. Morton takes over a freight train, captures the crooks, and rescues Helen and the gems.
A pair of crooks steal a valuable package, hold up the crew of a freight engine, and compel the engineer to aid their escape. Learning this, Helen climbs into the cab of a locomotive standing on a siding and takes up the chase.
Billy Warren, timekeeper on the construction job, arouses the enmity of Brent and Easton when he resents their bullying of the other men. Pay day finds the men celebrating in riotous fashion, and Brent in a crazed moment breaks into the station and attacks Helen. Her cries bring Warren, who trounces the bully.
Brent, the night operator has been knocked unconscious by a piece of lumber projecting from a passing freight, and has been rendered temporarily insane. Meantime, a furious storm arises, a track walker discovers a washout and wires a warning to Helen, who sets the danger signal for the Limited which is due in ten minutes.