On a small tropical island in the South Pacific, David Bowman (Alan Baxter), a young American planter, finds himself pitted against a ruthless Japanese agent, Matsuru (Ernst Deutsch). He learns through Toni Chase (Gertrude Michael)an American girl who runs a dance-resort on the island that Matsuru has established a powerful-and-hidden short-wave radio station near his home, and American ships have been attacked in that part of the Pacific with deadly effect.