The shows take their name from the police term dragnet, a system of coordinated measures for apprehending criminals or suspects.

Webb reprised his radio role of Los Angeles police detective Sergeant Joe Friday.

The ominous, four-note introduction to the brass and tympani theme music (titled "Danger Ahead"), composed by Walter Schumann, is instantly recognizable.

Friday rode with various partners until settling on Ben Alexander as detective Frank Smith, providing some sporadic comic relief.

Friday is a dedicated police officer, and pretty much a straight-arrow type, though occasional flashes of a dry, mordant sense of humor show through.

He can be sympathetic towards victims, or even towards some criminals whose crimes are a result of difficult circumstances, but he has little patience with those he thinks are lying to him.

Amongst the many recurring discussion topics are Frank's generally warm but occasionally comically-strained relationship with his wife Fay; his sincere but sometimes bumbling attempts to relate to his children; his pride in his cooking (especially his "famous" omelettes); his somewhat dubious health advice; and his long-running frustration with his mooching, ne'er-do-well brother-in-law Armand.

Harlan Stall (a precinct co-worker), beginning in season 2, Olan Soule took on the role of Ray Pinker.

Pinker is seen in numerous episodes from seasons 2 through 8, helping to examine crime scenes and offering various forensically obtained clues to the detectives.

When they were posted to Robbery detail, seen occasionally in seasons 2 to 5 was the captain of that department, the milk-drinking Harry Didion.

The milk-drinking was suggestive of an ulcer, perhaps due to the pressures of the job, but Didion (based on a real LAPD captain of the same name) did not show any weakness or indecision in the performance of his duties.

Thad Brown was the chief of detectives (played by Raymond Burr in the pilot, thereafter by several other one-shot actors); R. A. Lohrman was the head of the homicide squad.

While working on the radio drama, Webb formed a friendship with LAPD chief William Parker, and agreed to allow the police department to censor Dragnet in exchange for story ideas.

Friday and the police force often encountering the seedy side of Los Angeles, with a steady succession of callous fugitives, desperate gunmen, slippery swindlers, and hard bitten women.

Most of the cast members were veteran radio actors who could be relied upon to read the matter-of-fact dialogue naturally.

Webb used most of his ensemble players again and again in different roles: Jack Kruschen, Vic Perrin, Harry Bartell, Art Gilmore, Peggy Webber, Barney Phillips, Herb Ellis, Carolyn Jones (then billed as Caroline Jones), Clarence Cassell, Virginia Christine, Ralph Moody, Kathleen Freeman, Stacy Harris, Natalie Masters, Virginia Gregg, Olan Soule, Herb Vigran, Peter Leeds, Sarah Selby, and many others.

Webb staged each story with newsreel-like authenticity, enhancing the visual action with extremely tight close-ups (unheard of in the days of tiny television screens), location photography, and unusual camera angles.

Although still using convincing dialogue readings, the new Dragnet lost much of the documentary appearance, and film noir ambience.

Just before the show took its final commercial break, the show's announcer would inform the audience of something related to the case, usually the opening date on which the perpetrator's trial would take place in the Los Angeles County Superior Court (this would be accompanied by an onscreen card so the viewer could read along).

In rare cases, where the perpetrator was found guilty of murder and the death penalty was applied, the place and method of execution was noted on screen.

Over 200 of the 276 episodes of Dragnet have not seen broadcast since the late 1960s, or received any kind of home video or DVD release.