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. The deranged Brent enters, throws Helen into a closet, and sets the semaphore arm to swing back to 'clear'. Helen escapes by prying up the flooring, makes her way to the bottom of the tower, and swings the semaphore back to 'stop.' Seizing a lantern, Helen then rushes to the scene of the washout, crosses the swollen stream, and stops the Fast Freight in the nick of time, on the brink of the ruined trestle; meantime the Limited has been stopped by the semaphore, and Helen becomes the heroine of the day.