FBI has to track down spies who are broadcasting shipping information to Japanese submarines using a new type of radio transmitter. Their plan is to have all the radio technicians in the area fired from their job, so that one will find employment with the bad guys when the transmitter breaks. Dumb idea, but it works!

Bargain basement World War 2 film held together by Arlen's likable everyman and some interesting casting, mainly Dwight Frye in nearly his last role, but also the underrated Miljan in a dual role. Some of the better points of the film--a surprisingly good car chase sequence, for example--are offset by hokey elements that you only find in cheapies of this era: the Japanese spoken by the submariners is merely some bits of dialogue played backwards, footage of a Navy destroyer being sunk (probably footage from the 1930 film The Seas Beneath) is shown, then followed by a spinning headline stating "Another tanker destroyed," a heroic kid saves the day by staying up past bedtime listening to his ham radio, and so on.

To up the emotional ante, Arlen has a supposedly adorable little girl in his care who also happens to be vaguely and deathly ill. The fact that she is played by perhaps the worst child actor in the history of cinema rather detracts from the sub-plot, though. That being said, the dialogue is pretty sharp, such as when the main baddies salute "Heil Hitler!" and sub commander Biberman blithely states, "The submarine accomplishing this work, gentlemen, is Japanese." Nothing beats the first two minutes of the film, though, where radio inventor Van Sloan refuses to give up his invention to the baddies and runs, only to be shot in the back and then run over by a tractor and harrow that convieniently happens to be passing by!