Richard Arlen was a Paramount contract star dating back to the silent era, where he gave an emotional performance in Wings, one of the most famous of silent films. During the 1940s he became the rugged and stoic action hero of “B” movies, designed to entertain on a slim budget. Some were subpar, but this one is a nifty little wartime “B” with a good story from Maxwell Shane. Because it is a “B” from a major studio rather than a Poverty Row entry, it’s a little tighter and leaner than most. The streamlined direction from Frank McDonald and pleasant leading performances keep you interested.

A secret transmitter is being used by German spies to pinpoint oil tankers for Japanese subs to sink, slowing the war effort. The F.B.I. decides to have several topflight radio engineers laid off and see if any are approached. The firing comes at an inopportune time for our stoic hero Arlen, as his daughter Tina needs a costly operation.

Anne Patterson (Wendy Barrie) just happens along so he can save her from a scripted purse snatching, and she can keep an eye on him. When he’s offered work which unbeknownst to him is helping the enemy with their transmitter, her growing feelings for him and his small daughter come into play.

When an F.B.I. man gets knocked off at his place, and the transmitter is stolen, Arlen goes into action to discover what’s going on. There’s a nice twist when he blows Anne off, pegging her for a Fed who has simply been spying on him.

Nice touches, such as a waterwheel being used during an exciting little chase, help elevate this nifty “B” above most of Arlen’s other low-budget action films from the 1940s. Once Anne catches up with her man again, this film gets even better — even if it is a little cornball. A room full of steam and a young ham radio operator who knows Morse code come into play before this one is wrapped up.

Submarine Alert is swiftly paced, has a few stylish touches, and is played out so sincerely it manages to avoid those eye-rolling moments you get in many programmers from the era. It won’t grab you, but it will keep you interested on a rainy night, rewarding the viewer with a dash of excitement near the end. Nils Asther is among the cast, and fans of Gunsmoke can catch a young Milburn Stone in a small part. A nice little "B" film that does what is sets out to do. ( )

Nazi spies use a stolen shortwave transmitter prototype to broadcast top secret shipping info to an offshore Japanese sub. To nab the spy ring, the Government has the West Coast's top radio engineers fired and shadowed to see if the Nazis recruit them to complete work on the prototype radio. Radio engineer Lew Deerhold, a resident alien without a job to pay for his adorable little ward Gina's life-saving operation, falls prey to the spy ring, and is swept up in a maelstrom of deceit and danger (fonte: Imdb)

Nazi spies use a stolen shortwave transmitter prototype to broadcast top secret shipping info to an offshore Japanese sub. To nab the spy ring, the Government has the West Coast’s top radio engineers fired and shadowed to see if the Nazis recruit them to complete work on the prototype radio. Radio engineer Lew Deerhold, a resident alien without a job to pay for his adorable little ward Gina’s life-saving operation, falls prey to the spy ring, and is swept up in a maelstrom of deceit and danger. (fonte: imdb)