Having been marooned on an isolated island as a child, Dea grows to adulthood without human contact, her only companion being the chimp"Koko." Years later, on a South Sea island, Skipper Joe, a former bookie who has traded chasing dark horses for the pursuit of black pearls, meets Johnny Potter, a former Navy man who has lived in a drunken stupor since being kicked out of the service. The skipper tries to convince Johnny to sign on as his navigator, but Johnny refuses to return to the sea. However, after a bar room brawl with the savage Kehi, Johnny is knocked unconscious and is shanghaied by Skipper aboard his rusty old submarine. The men are chased from the harbor by Kehi, who is furious because Mekaike, one of the skipper's men, has stolen his black pearl earrings. After running out of oil because Mekaike has forgotten to refuel the tank, they reach the island inhabited by Dea, where Johnny collapses on the beach in a drunken stupor. The skipper leaves his friend on the beach, where Dea and Koko find him and take him to their tree house to recover. When the skipper returns to the beach, he thinks that Johnny has been washed out to sea. As the skipper and his men build a boat to leave the island, Dea begs Johnny to stay, but fearing that he is doomed to die an early death from alcohol, he refuses. Finding his way back to the beach, Johnny arrives just as Mekaike leads a mutiny against the skipper. After tying Johnny and the skipper to a tree, the men steal the submarine, only to drown when they dive with the hatch open. Stranded, Johnny and the skipper continue building their boat until Kehi tracks them down and sets fire to the island. As the flames consume the foliage, a typhoon roars in from the sea and floods the island, leaving a lifeboat behind in its wake. Dea, Johnny, the skipper and Koko then board the little craft and sail off to civilization.