AllMovie

When his father (Guy Bates Post) is killed by a poisoned dart, Geoffrey Prescott (Tom Tyler assumes the guise of The Phantom, the benevolent ruler of fifteen jungle tribes. Meanwhile, at Sai Pana, an expedition lead by Professor Davidson (Frank Shannon), his niece Diana Palmer (Jeanne Bates) and her fiancé Byron Andrews (Guy Kingsford), is seeking to locate the untold riches of the lost city of Zoloz. The professor holds three pieces of a map to the secret location, Singapore Smith (Joe Devlin) an additional three but the most important piece of the puzzle, the centerpiece, is still missing. Smith has his henchmen steal the professor's three keys in a way that casts aspersion on Geoffrey Prescott, hitherto part of the expedition. The latter, however, has his hands full with a couple of jungle crooks hired by Dr. Max Bremmer (Kenneth McDonald), the secret head of a group of foreign saboteurs, who believes The Phantom to be a mere mortal playing on the superstition of the natives. Bremmer has one of his hecnhmen lead the novice Phantom on a wild goose chase straight to the Devil Swamp. As The Phantom sinks ever deeper into the mire, a hungry alligator attacks him.