Akim Tamiroff, Paramount's resident crime lord, runs all the illegal gambling activities in a major city. Reporter Lloyd Nolan struggles to get the goods on Tamiroff, but runs up against a stone wall until he meets sexy but tough nightclub singer Claire Trevor (obviously dubbed). Trevor is anxious to avenge the death of her innocent sister (Helen Burgess), who was done in by Tamiroff's henchmen. Though only a "B" picture budget, King of Gamblers was given "A" treatment by director Robert Florey. The film was part of an unofficial Paramount series based on the FBIs J. Edgar Hoover book Persons in Hiding.