en Cuevana 3. The railroad is building a new line, but the workers are unhappy. That's because one of the board members, hoping to oust the man in charge of the project (Rapley), has a saboteur on site. Rapley's daughter, Rose, sneaks out to the project to become their telegraph operator and, with the help of the supervisor, "Sunrise" Smith, eventually discovers the plot and helps catch the bad guys amid several thrilling train chases.