Sgt. Mike Kincaid of the French Foreign Legion learns, from a Riff prisoner, that an attack will soon be made by the villainous Hussin on the Legion's outpost of Tarfa. Kincaid volunteers to lead nine other Legionnaires on a mission to delay Hussin's attack till reinforcements arrive. When he discovers that Hussin plans to marry Mahla, a girl from a rival tribe, in order to build a coalition against the French, Kincaid kidnaps Mahla. Hussin forcefully takes her back, but by now his planned attack on Tarfa is crumbling and Mahla has begun to fall in love with Kincaid.

Paris plumber Elmer Tuttle is enlisted by socialite Patricia Alden to help make her lover Tony Lagorce jealous. With the help of his friend Julius J. McCracken and through the high society contacts he has made through Patricia, Elmer hopes to find financing for his latest invention, a pistol with a range-finding light. Comic complications ensue when Elmer's effort to interest a military leader is misconstrued as an assassination attempt.

Cutthroat pirate William Kidd captures Admiral Blayne's treasure ship and hides the bounty in a cave. Three years later, Kidd, posing as a respectable merchant captain, offers his services to the King of England. Seeking a social position, Kidd also negotiates for Blayne's title and lands, provided he can prove Blayne was associated with piracy. Launched upon his royal mission, Kidd is unaware that Blayne's son Adam is among the crew, determined to clear his father's name.

Mike and Tony Petrakis are a Greek father and son team who dive for sponges off the coast of Florida. After they are robbed by crooks, Arnold and the Rhys brothers, Mike decides to take his men to the dangerous 12-mile reef to dive for more sponges. Mike suffers a fatal accident when he falls from the reef leaving Tony to carry on the business. But now he has a companion, Gwyneth Rhys.