Alice Grayson's uncle develops a wireless torpedo that can be controlled by radio. After he announces his invention to several of his colleagues, two of them murder the scientist, steal the blueprints and prototype, and make plans to sell both to the highest bidder. When Alice discovers the identity of the thieves, the intrepid heroine, with the help of Bob Moore, her two-fisted boyfriend, desperately tries to recover the plans and torpedo before enemy countries can unleash the torpedoes against American ships.