An investigation is held at Hart's Junction to solve the blowing up of ammunition trains. Helen, the operator, is questioned by a detective. Belding, the "brains" of the dynamiting gang, and Steele, his accomplice, approach and note what is taking place. Helen is excused. Crossing the platform to meet the incoming train. Helen sees Belding and Steele. She gets on the train for Fardale. Belding and Steele get in an auto. Wertz, another member of the gang, "listens in" on the wire near Fardale and gets information regarding the munitions trains. Merkel, a lineman detective, sees Wertz. Merkel attacks him. In an exciting chase, with the gang fleeing on a freight, Helen climbs a telegraph pole and gets on a carryall arrangement which runs along a cable stretched between two poles on either side of the tracks. She starts the carryall, and when she is over the train one of the gang shoots and cuts the rope. She drops and lands atop one of the cars. She recovers and succeeds, with the aid of others, in capturing the plotters.
—Moving Picture World synopsis