Big-screen spin-off of the immensely successful radio-TV "Dragnet" show has L.A. cops Sgt. Joe Friday (Webb) and Officer Frank Smith (Alexander) investigating the murder of a former syndicate member. Webb's direction is spotty, notably when the screenplay bogs down into the tedium of cop life, or during a fight scene unwittingly designed to provoke yuks. Acting honors go to Virginia Gregg's sodden syndicate widow. Webb is his usual deadpan cop, with Alexander as his dronelike sidekick (later replaced in a 1969 TV film by Harry Morgan as Joe Gannon--a better choice). Based on actual L.A. police files, the film manages to still deliver plenty of suspense. The theme beat for the series and this film--"dum-de-dum-dum"--was first used in Robert Siodmak's marvelous THE KILLERS (1946).