Submarine Alert is a 1943 American film directed by Frank McDonald, produced by Pine-Thomas Productions and released by Paramount Pictures.

The film stars Richard Arlen, Wendy Barrie, Nils Asther, Roger Pryor, Marc Lawrence and Ralph Sanford.

Needing money, he applies for work at a radio repair shop, where he meets Ann Patterson (Wendy Barrie), the victim of a purse snatching.

After coming back to his apartment, his new boss is there with Dr. Arthur Huneker (Nils Asther) and his assistant Vincent Bela (Marc Lawrence).

Lew is offered a job by Huneker, a Nazi spy commander who needs someone to repair a top-secret stolen radio transmitter.

At the doctor's hot springs resort, Lew and Ann join forces, but are captured and locked in a steam room by Huneker.

Before they are killed by the steam, Lew devises a transmitter and sends an SOS that is picked up by a young boy whose father calls the FBI.