The bad blood existing between Reardon and Haley results in a fight in which Reardon is worsted. Reardon, vowing vengeance, climbs back aboard his engine while Haley resumes his station. The fight is witnessed by a number of railroad men. In climbing back to the water tank, Haley stumbles and falls between the cars. By a miracle, the man escapes death, but the shock leaves him temporarily demented. By the time Reardon discovers that his fireman has disappeared from his station, the train is several miles from the scene of the accident. A search is made for the missing man, but since Haley has taken refuge in the underbrush, it proves futile. Although Reardon is suspected of having done away with his fireman, lack of evidence keeps him out of the law's clutches. Shortly afterwards, Helen, in passing between two boxcars, comes upon the insane fireman. Leaping upon her, Haley knocks the girl unconscious and then lashes his victim to the driving rod of the freight engine. Climbing into the cab, Haley opens the throttle. The startled trainmen see the engine dashing down the track and wire ahead, ordering the tracks to be cleared. Reardon thus becomes aware of the runaway. A steep grade causes the engine to slow down as it approaches the crossing where the engineer waits. A flying leap and Reardon boards the locomotive. Haley leaves his throttle to attack the engineer. Reardon, however, catches the insane man squarely upon the jaw and knocks him unconscious. Springing into the cab, the engineer brings the locomotive to a halt just in time to avoid crashing into the Hendon express at the Thomas Crossing. Leaping to the ground, Reardon cuts the cords which bind Helen. The girl is unconscious as the result of her frightful experience, but soon revives.