After his brother Robeson disappears without a trace while exploring Africa in search of a legendary 'white tribe', Allan Quatermain decides to follow in his footsteps to learn what became of him. Soon after arriving, he discovers the Lost City of Gold, controlled by the evil lord Agon, and mined by his legions of white slaves.

Two divers find a treasure map, which apparently points to a sunken treasure below the ocean. They hire a professional to help them get the gold but this guy turns out to have a few secrets of his own.