Benedict Hisston is a foreign agent, part of a conspiracy to destroy the Panama Canal and the US Navy's Atlantic Fleet. He attempts to acquire information about mine placement in the Canal Zone from Captain Richard Decatur but fails. That information is essential to the conspiracy's success and so he then hires vamp Peg Williams to obtain the intelligence through seduction. Decatur is not fooled and obeys the "silent command" of the Chief of Naval Intelligence to play along with the spies without revealing his purpose to friends or family. He is court-martialed, stripped of rank, and dismissed from the Navy after he strikes an admiral. His association with Williams estranges him from his wife but earns him the trust of Hisston and the other spies. When the conspirators are ready to enact their plan, he travels to Panama with them. He thwarts their attempt at sabotage, saving the canal and the fleet. He is then reinstated into the Navy, reunited with his wife, and honored by the nation for his heroism