An unprincipled inventor uses hypnotism to force others to steal the plans of an important radio beam aerial bomb. The bomb can be propelled through the air via remote control and sink ships several hundred miles at sea. The bomb would help keep enemy battle fleets from encroaching on American shores. The crooked inventor is a rival of the inventor of the bomb, who is suspected of trying to steal the plans, although they are his own. A G-man named Kelly is assigned to investigate the theft, and eventually realizes who the true inventor is. A young secretary, with whom the G-man falls in love, is also suspected for a while, but is later cleared.