Espionage, war and romance in the Far East in 1904: Russian naval officer Boris Ranewsky marries Youki, the sister of a fanatical Japanese officer, but war is imminent.

Tom Finberg and Nick Dorland, two highly competent divers working for the Caribbian Oil Company, have been the best friends in the world since the day they met. But this wonderful friendship is endangered by their falling in love with the same young woman, Juana, the young owner of a hacienda. Worse, following a misunderstanding, generated by the belle's scheming uncle, Pedro de Alvarado, the two men fall out with each other. But when Tom is trapped under the surface of the burning ocean, Nick finally comes to his rescue.