On the island of Tankana in the South Pacific, a violent storm rages as Val Stevens Humphrey Bogart and Lucille Gordon Margaret Lindsay exchange their vows in a small home ceremony. The celebration is abruptly cut short by the news that a ship is sinking on an offshore reef, and Val hurries through the last lines of the ceremony before plunging into the churning surf. From the wreckage, only two survivors are pulled from the sea: the ship’s captain, Captain Deever Paul Graetz, and the man who had chartered the boat, Eric Blake Donald Woods.
Blake comes ashore cheerful, but the captain’s duplicity is exposed when he is caught by the island’s doctor, Dr. Hardy E. E. Clive while attempting to steal money that belongs to Blake. Val refuses to tolerate the threat and banishes the captain on the next steamer. With his pearl venture hanging by a thread, Val learns that his native divers refuse to work after two of their men drown, threatening the livelihood of his business. To prove there is nothing to fear, Val suits up in a diving outfit, tethered to the boat and fed with air by a hand pump, and descends toward the spot where the natives disappeared. Beneath the surface, a tense struggle unfolds as he is attacked by a giant octopus and fights for his life, while on the surface his two native head men seem to be plotting against him. In a critical moment, Eric dives in to help, pulling the tether so Val can be hauled back to safety. The rescue strengthens a growing bond between the two men, each having saved the other.
Since their first meeting, the captivating Lucille has drawn Eric to her warmth and charm, and in the shadows of moonlit nights the island’s doctor nudges him toward following his heart toward Lucille. Yet danger intensifies when Eric rescues Val a second time, as his two head men try to seize Val’s pearl cache before it can be shipped out on the anticipated steamer. Val, sensing opportunity, urges Eric to stay and become his partner, but Eric refuses, insisting that he must sail on to his destination.
Later that night, the doctor reveals to Eric that he suspects Eric is a detective sent to capture Val, who is wanted by the authorities for a murder. Eric insists he has reconsidered, now believing in Val’s innocence. Eavesdropping from the bushes, the captain—having slipped back onto the island on a supply boat—misreads the situation and tells Val that Eric is the wanted man and will be turned in for a $5,000 reward. Val, furious, confronts the captain only to learn the truth from the doctor, who clarifies the matter and defuses the false claim.
Undeterred, the captain returns with a pistol and holds everyone at gunpoint. In a dramatic turn, Lucille’s grandfather steps into the room and shoots the captain dead, changing the stakes entirely. Faced with this turn of events, Lucille vows to remain with Val rather than flee with Eric. On the quay the next morning, as the steamer approaches, Eric weighs his report and tells the doctor that he will simply write that the wanted man is dead. With that decision, he boards the tender and waves farewell, leaving the island and its tangled loyalties behind.
