In order to win back his girlfriend, Mike Shayne promises to give up his detective practice and get a job as riveter in an aircraft plant. He quickly finds himself investigating the theft of industrial diamonds from the plant's safe and, utilizing a variety of false identities, traces them first to a dress factory and later to a Hawaii-bound ocean liner. Escaping several attempts on his life, he is able to uncover a Nazi smuggling ring, but the location of the missing diamonds continues to elude him.

Three men survive a plane crashes on an uncharted Pacific island, south of Tahiti. One falls in love with the the daughter of the tribe's leader, heiress to the throne after the death of her brother, who is as savage as her pet leopard. The others try to devise a plan to rob the tribe's gold.