Phony missionary Virginia Mayo, in cahoots with crooks Dennis Morgan and David Farrar, plan to steal a fortune in black pearls from the suspecting islanders. They soon discover these pearls rest in an underwater shrine guarded by a giant octopus, and just as they are about to make off with the booty, the natives see through the guise and attack them, killing one of them and burning their schooner. Who gets killed and what will be the destiny of the two survivors?

Virginia Mayo stars as Rita Delaine in this melodrama set in the South Seas. When schooner-skipper Dan Merrill (Dennis Morgan) awakens from a blow to the head, he finds that he and his boat have been taken over by two of his friends, Rita Delaine and Bully Hague (David Farrar), who want him to join them on an expedition to a remote Pacific island, where, they believe, the local natives have hidden a vast fortune in black pearls.Their appearance on the island halts the marriage of George (Lance Fuller), the half-breed son of the island's white ruler Tuan Michael (Basil Rusdael) and Momu (Lisa Montell) daughter of Halemano (Murvyn Vye), a warrior chief. Tuan Michael orders the intruders to leave, concerned that they will disturb the tranquility of his kingdom. But Rita claims that their craft is too damaged to be seaworthy, and will have to be docked for repairs. She quickly charms the island people, slipping questions about the black pearls into her banter with them. She concentrates in particular on George, who, completely mesmerized by her, reveals that black pearls reside in a chest on the ocean floor guarded by a giant octopus. Camp classic in which the octopus has the best dialogue.