The Green Goddess is a totem worshiped by the primitive natives of a lost city deep in the jungles of Guatemala, which contains both a fortune in jewels and an ancient formula for a super-explosive which could threaten the world in the wrong hands. From Africa, Major Martling launches an expedition to find the Goddess and place its secret in safe hands. So does Ula Vale, whose fiance died attempting a similar expe- dition, despite the warnings of her lawyer Hiram Powers, who secretly wants the Goddess' contents for himself and has dispatched Raglan, a mercenary, to get it for him. Aboard ship to Guatemala, they meet Lord Greystoke - aka Tarzan - on his way to the same locale to find his old friend d'Arnot, whose plane reportedly crashed near the lost city. On reaching Guatemala, Tarzan, the Martling party and Ula learn of Raglan's devilish mission and that he has a good head start on them...