Professor Campbell's expedition into the hills of Libya obtains a papyrus which might reveal the hiding place of the Golden Tablets of Hippocrates, containing lost medical secrets. Also in the region is intrepid Nyoka Gordon, still seeking her father, lost on a previous expedition. She alone can translate the papyrus, which directs our heroes through deadly perils (including the Tunnel of Bubbling Death) into the land of the Tuaregs.