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. During World War II, with shipping being sunk by submarines and with an American scientist working on radio technology killed by Nazi spies, FBI agent G. B. Fleming (Roger Pryor) comes up with a plan to catch the Nazis. He believes that radio signals are alerting the Germans about ship movements. His plan is to fire all the local radio specialists, who likely will seek any employment, including working with the enemy. Tailing the jobless radio men will help the FBI find the Nazis.