Adventurer Johnny Weissmuller Johnny Weissmüller (playing himself) is hired by Egyptian archaeologist Ellen Marsten Jean Byron to traverse the African jungle of Baku, hoping to rescue an acquaintance, Marro Ben Chapman, from captors—pygmies who call themselves the Moon Men. These ritualists are devoted to the Moon Goddess Oma Helene Stanton, an apparent immortal whose only weakness is sunlight, and Marro has been chosen to serve as Oma’s chief religious official. The setup blends adventure, danger, and a dash of mysticism as the trio prepares for a perilous journey into uncharted terrain.
Joined by Marsten's friend Bob Prentice William Henry, the expedition presses deeper into the jungle, confronting the unknown at every turn. They locate Marro and urge him to escape, but tragedy strikes when he dies the moment he steps outside the jungle’s edge. In a tense exchange with a pygmy named Damu Billy Curtis, Weissmuller learns that Marro had been dosed with a voodoo potion designed to kill him if he attempted to flee Baku, a cruel safeguard that keeps the captive under the Moon Men’s control. Just as the truth dawns, the Moon Men surge forward and overpower the expedition, sealing their fate. Prentice is chosen to fill Marro’s ceremonial role, while Weissmuller and Marsten are hauled toward Oma’s temple, a place heavy with ritual and danger.
Inside the temple, they encounter a pair of sinister leaders: Santo Myron Healey and his right-hand man Max Frank Sully. The two men force Weissmuller to navigate them into Oma’s lair, where jewels glitter among ancient stones and the air hums with mystery. Oma’s presence is both awe-inspiring and fragile, and the stones hint at wealth beyond imagining. Weissmuller, weighing the odds and the lives of his companions, makes a selfless choice and sacrifices himself to give the others a chance to escape. He entrusts Prentice with the task of contacting the mainland police the moment they reach safety. In a fit of avarice, Santo pockets a significant portion of the loot and tries to flee, only to be halted by the Moon Men, who unleash a ferocious lions’ den in a brutal, chaotic turn of events. Santo and Max are consumed by the carnage, while the remaining travelers slip away from the collapsing fortress of treasure and ritual.
With time running out, Weissmuller pleads with Oma to reveal a fast exit from Baku. She reluctantly complies, but her mercy is short-lived; dragged toward the sunlit open, the Moon Goddess dissolves into fine dust, vanishing from sight and leaving a bitter reminder of the sun’s deadly power. Back in civilization, Prentice laments the lack of hard evidence proving Baku’s existence, a practical frustration that contrasts with the legendary aura of their ordeal. In a final, small twist, Weissmuller’s loyal chimpanzee Kimba is shown carrying a diamond pendant, a quiet token of the adventure that hints at a mystery lingering beyond the jungle’s edge.
