Helen, discharged by the superintendent without justification, comes to the rescue when a flat car, loaded with dynamite, is tearing to certain destruction down the grade, bearing the mischievous son of the superintendent. She boards her motorcycle and races down the track. The drawbridge is being raised as she reaches it, but without a second's hesitation she speeds across, the motorcycle whirling through the space separating the bridge and tracks. Helen then boards an engine and reaches a railroad trestle before the runaway flat car. Hanging head downward from the trestle by means of a painter's rope, she succeeds in grasping the superintendent's son and swinging him to safety. A second later the flat car, sent on a siding by the railroad men, has struck a boxcar and exploded with a deafening roar.