During World War II, with shipping being sunk by submarines and with an American scientist working on radio technology killed by Nazi spies, Federal Bureau of Investigation 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.