Universal Pictures 63rd sound-era serial (between "Mystery of the River Boat" and "The Masater Key") finds that Nazi agents are trying to arouse the tribes of the middle jungle in Africa to revolt against the British. Americans Bob Elliott (Edward Norris) and Chuck Kelly (Eddie Quillan) arrive to help the British agents. Lothel (Ruth Roman), the mysterious Queen of the Jungle, appears and disappears always in the nick of time to save them, and also Pam Courtney (Lois Collier), niece of the explorer Alan Courtney (`Boyd Irwin` (q)). Dr. Elise Bork (Tala Birell) and her henchman Lang (Douglass Dumbrille) are the Nazi chiefs, posing as scientists. Lang has great influence on some of the tribesman, especially with Chief Maata (Napoleon Simpson`) who wants to keep Kyba (Clarence Muse) from becoming judge over all the tribes. A Secret Sword is the key to the ruler of the jungles, and the holder of this secret is sought by both the British and the Nazis.