Captain Leandro Dupré, skipper of the schooner "Niña bonita," is having the worst streak of bad luck since he arrived in the Melanesian Islands seeking his fortune. After losing all of his savings gambling, and breaking up with his girl friend, Mariana, he has also lost the schooner in a race against rival captain Korff when he stopped to rescue a castaway. While Korff celebrates his victory, the castaway insists upon rewarding Leandro with a handful of pearls and tells him where he can find more. Later, as soon as Leandro has recovered his boat by selling the pearls, he sets sail secretly and heads for a group of islands inhabited by cannibals. Mariana stows away on board. From inside a diving suit, Leandro marvels at the amazing pearl bed he discovers, without realizing that, above, Korff has followed him and is preparing to take over his boat. However, the cannibals counterattack, rout Korff's men and prepare to sacrifice Mariana and Leandro's crew. When Leandro emerges from the depths, however, encased in the diving suit, the cannibals think that this strange monster must be the sea god and obey Leandro's orders to release the crew.