The first of the five films where Bill Elliott played a detective lieutenant in the L.A Sheriff's department, Dial Red "O" (the correct title with the number 0 (zero), as on a telephone dial, shown in ") opens with war-torn veteran Ralph Wyatt getting word that his wife is divorcing him, and he flees the psychiatric ward of the veteran's hospital, wanting to talk to her. His escape touches off an all-out manhunt, led by Lieutenant Andy Flynn of the sheriff's department.

Brett Wade, gambler, gunslinger, and classical pianist, is wounded in a gunfight with the Ferris clan; the doctor finds signs of tuberculosis. En route to Colorado for his health, Brett stops in Socorro, New Mexico along with Ferris gunfighter Jimmy Rapp. Sheriff Couthen fears another shootout, but what Brett has in mind is saving waif-with-a-past Rannah Hayes from a life as one of Dick Braden's saloon girls.

A man has kidnaped an engraver and has him forging Mexican bills. He captures wild horses supposedly to sell for hides but uses them to transport the bills across the border. Police captain Juan Reyes (Richard Avonde) is posing as a bandit to uncover the counterfeiters smuggling fake pesos into Mexico, and is assisted by feisty youngsters Red (Michael Chapin) and Judy (Eilene Janssen), who are trying to protect the wild horses being used by the gang. The kids suspect that rancher Big John Harkins (Roy Barcroft) is the leader of the gang and that he is forcing Mexican artist Espinosa (Julian Rivero) to help him.

Charles "Durango" Starrett and his pal Smiley Burnette go after smugglers. Our heroes travel incognito across the Mexican border to beard the leader of the gang in his den.