In the time of Hannon, the Grand Admiral who first explored Africa, our companions learn that the men of HANNON have been attacked by swift demons, captured and are forced to exploit a gold deposit on the edge of a river in Africa. But who are the mysterious individuals commanding the "furry demons"? The masters of the gorillas are the descendants of Phoenician sailors who made the trip around Africa, under the reign of pharaoh Nechao II, a century and a half before that of Hannon. Following a shipwreck, abandoned by their own, they plunged into the land and founded a new "kingdom", patiently training the gorillas so that the ferocious beasts obey them. The descendants vowed a fierce hatred for humanity which forgot them. The gold fever, the humid atmosphere of the place, the seclusion, made them half mad.