Ramu (Jon Hall) and his fiancée Tollea (Maria Montez) are due to be married, but before the ceremony can begin Tollea is kidnapped and forced against her will to return to the island of her ancestors. Her evil sister Naja (Maria Montez) rules her subjects with an iron will, helped by the poisonous venom of the ceremonial cobra. Ram and his friend Kado (Sabu) set out to rescue Tollea and land on the forbidden island where all strangers are killed.

As the island's volcano begins to erupt the evil Naja decides to sacrifice some of her subjects and the two strangers in order to placate the angry volcano god. But when Naja learns that her prisoner Ramu is engaged to her hated sister, she decides to have him for herself and eliminate her sister instead.