A great safari comes to Africa to make a movie, struggling across the veldt and through the jungle in great ten-ton trucks, equipped with all the advantages of civilization. But now it is halted, almost destroyed by the poisoned arrows of the savage Bansuto tribe. There is no way to return. Ahead lies the strange valley of diamonds, where hairy gorillas live in their town of London on the Thames, ruled by King Henry the Eighth. And behind them comes Tarzan of the Apes with the Golden Lion, seeking the man who might have been his twin brother in looks—though hardly in courage!

In the wild, unexplored coastal jungles of West Africa lives a wild human boy named Tarzan, the adopted son of a tribe of fierce almost-human anthropoid apes - but in reality, the unknown heir of a wealthy and titled English noble family. Then one day, a small party of American treasure-seekers is marooned on Tarzan's beach, including a lovely Baltimore belle named Jane Porter.

When the hard-won peace of the primitive Empire of Pellucidar is shattered by the invasion of the fierce Korsar sea-rovers, Emperor David Innes sends his caveman horde to battle. One of the bravest of his club-swinging warriors is Tanar the Fleet One. Despite the strange weapons of the invaders, David and his skin-clad band thrust back the Korsars and force them to flee in their ships--but with them they take several captives, including Tanar. But the bronzed warrior from the kingdom of Sari is no easy prisoner to keep.

With the African continent engulfed by World War II, John Clayton, Lord Greystoke, abandons his role as Lord of the Jungle in order to combat the spreading Nazi menace. Flying a P-40 Tomahawk warplane, Clayton is sent on his first mission: to rescue the missing British Military Intelligence officer code-named Ilex. But the daring task plunges him into his savage past after he’s forced down in a lost land that seems hauntingly familiar. 

In this sequel to At the Earth's Core, David Innes vows revenge and returns to the Inner World of Pellucidar to rescue the beautiful Dian, who had been torn from his arms by trickery. However, his return trip places him far from the land of his beloved and he is forced to undertake a desperate journey thousands of miles across the fierce inner earth to reach her.