"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. The crew walks right into "Red's" trap, and the members are made prisoners. Spencer suspects trouble, and hurriedly slams the door of his car, barricading himself in. The conspirators, temporarily foiled, plan a dastardly scheme. The two last cars of the freight are uncoupled and started down the grade, when, by skillful maneuvering they succeed in causing a collision that stuns the guard and all but smashes the treasure car. Helen, arriving for duty, senses something amiss as she nears the station, and learns the truth before she is seen by "Red's" aides left to guard the train crew. Running down the track she boards the engine and sets out after the treasure car. By a leap to the car, and her quick wits she succeeds in frustrating "Red" and in bringing the gang to justice.