Gwendoline comes to China with her maid Beth to find her missing father. She runs into trouble with the Chinese Mafia, but is rescued by the adventurer Willard. He agrees to take both women with him to the land of the Yik-Yak, where the rare butterfly that eluded her father may be found. After daring boat rides, battles with pirates and desert crossings, they reach a secret underground city, which is dominated by semi-naked amazons in leather armor. After the activation of a volcano, Gwendoline, Beth and Willard can escape, and on the run Willard manages to capture the elusive butterfly.