AllMovie

The Hidden Enemy concerns the efforts of a group of foreign spies to get their mitts on an experimental super-metal developed by scientist McGregor (George Cleveland). Astonishingly, neither McGregor nor his newspaper-reporter son Bill (Warren Hull) are aware of the spies' activities until the film is half over. Meanwhile, an exotic number named Sonia (Kay Linaker) poses as a rival reporter while trying to obtain McGregor's metal formula for mysterious reasons of her own. In keeping with Hollywood's policy of pre-war neutrality, the nationalities of the villains in Hidden Enemy are unidentified, though their accents are decidedly Germanic and Italian in nature.