This sequel to King Solomon's Mines is filled with the spirit of adventure. Thrilled by rumors of a lost civilization, three Englishmen decide to travel to the heart of Africa with their Zulu guide where they meet with continual peril: an attack by a cruel warrior tribe, the scorch of underground volcanic fires, and an encounter with a huge species of ferocious black crab. Exhausted and depleted of supplies, the men at last arrive at a mysterious city in the highlands of the interior. More problems arise when one of the Englishmen falls in love with one of the twin queens who rule the land.