Captured by a trio of thieves, Gwendoline is sold to a local casino owner, but, rescued by Willard, a mercenary adventurer, she is reunited with her maid, Beth, after the latter's abduction by the same thieves who had earlier kidnapped Gwendoline. Hired to transport an illegal cargo, Willard reluctantly agrees to take both women with him after Beth, withholding information vital to his livelihood, promises to divulge it only if he becomes their guide. Gwendoline, who has come to China to capture the butterfly that eluded her father, who'd staked his professional reputation as a scientist on obtaining the insect, offers Willard $2000 to take her and Beth with him to the land of the Yik-Yak tribe, in which the butterfly may be found. After escaping from a tribe of cannibals, the trio find the butterfly, but, as she is about to capture it, Beth is captured by the Yik-Yak, and Gwendoline and Willard must enter the all-women tribe's underground lair to rescue the maid. To ensure the survival of her tribe, the Yik-Yak's queen allows a victor among them to mate with any man who visits or is captured by the tribe. Aided by Beth and the queen's henchman, who is a scientist, Gwendoline, disguised as a Yik-Yak combatant, wins this right. As she has sex with Willard, the scientist activates the volcano inside which the Yik-Yak live, and he, the queen, and others of the tribe are killed as Gwendoline, Beth, and Willard escape. In the process, Willard is able to capture the elusive butterfly.