Within two years of its 1952 small-screen debut, the eight-year long (1949-1957) radio series Dragnet had become television's number-one rated program. Created by actor Jack Webb, the series broke new ground from the outset, offering radio listeners rare authenticity of experience as they "accompanied" the police in following a case from beginning to final sentencing. Each episode unfolded at a measured pace, as detectives Friday and Smith followed clues, interviewed witnesses both friendly and hostile, and checked with various branches of law enforcement for information. Documentary realism was a key element of the show's appeal, with Jack Webb's own deadpan delivery and opening gambit, "This is the city. Los Angeles, California," making the mundane routine seem hip and cool.

The idea for Dragnet came to Webb after he had played a police lab technician in Anthony Mann's He Walked by Night (1948). He shared a belief with that film's technical...