Based on

Movies like Mobs, Inc. (1956)

Captain Braddock of the Los Angeles Racket Squad schools a group of cadet policemen by telling them of three precarious and dangerous cases of con artistry. Included are tracking down a dance hall girl, who, together with a big operative, are thwarted in attempting a robbery; a racketeer fleecing a book publisher on a Trans-Atlantic voyage, and the tripping up of the plans of a phony land syndicate.