Based on a famous kidnapping, Show Them No Mercy concerns the jealousies and psychological problems of a gang of hoodlums awaiting ransom money. As the G-Men move in, the hideout is invaded by a young couple with a sick baby. “In the post-Code period, gangsters were all hoodlums (and implied drug addicts and foreigners!) and all the brains (and good looks) were on the side of the FBI. Titles like Don't Turn 'Em Loose, Muss 'Em Up, Let 'Em Have It and tonight's title left no doubt in the public's mind as to how gangsters should be treated! Show Them No Mercy is, by 1935 if not by 1984 standards, quite a rough and savage little picture, but it is unique in that its boy-girl protagonists are almost Hitchcockian innocents drawn into the web of a kidnapping plot.... (Cast and) photographic and scenario credits are unusually strong on good names.” William K. Everson