Pellucidar

Listen to At the Earths Core with a movie-style soundtrack and amplify your audiobook experience. Dr. Abner Perry (Peter Cushing) is an English scientist who has invented a massive drill that can dig deep into the Earth. Joined by his adventure-seeking American backer, David Innes (Doug McClure), Perry accidentally discovers an underground civilization of primitive humans who live in fear of telepathic flying monsters. David becomes intrigued by the beautiful native Dia (Caroline Munro), and must rescue her when she is chosen as a human sacrifice. 

A drilling machine experiment reveals Pellucidar, a hidden world 500 miles under the Earth's surface. A world with eternal daylight, living dinosaurs, and stone-age humans, ruled by an advanced reptilian race. 

When David Innes and his inventor friend pierced the crust of the Earth in their new burrowing device, they broke out into a strange new inner world of eternal daylight - a world in back of the Stone Age, where prehistoric monsters still lived, and cave men and women battled against cruel, inhuman masters. The story of what these two men did in that new world of Pellucidar makes At the Earth's Core one of Burrough's most outstanding best sellers.

David Innes is a young man who has just inherited a large mining company. An eccentric inventor, Abner Perry, convinces Innes to underwrite a project to build an 'iron mole,' claiming it will make them both wealthy. The mechanical beast works well, actually too well. On the maiden voyage, instead of digging for a few minutes and returning, they plunge straight through the earth's crust into the 'inner world' of Pellucidar.

At the Earth's Core by Edgar Rice Burroughs is a fantasy novel, the first in his series about the fictional "hollow earth" land of Pellucidar.

Convinced of the worthiness of a giant, earth-boring machine, David Innes becomes a willing participant in an experiment. On the machine's maiden attempt at boring through the Earth, David and inventor Perry are trapped in the control room as the machine turns into a runaway. It bores steadily down toward the center of the Earth until finally it penetrates into a strange, subterranean world. The two travelers are immediately welcomed by a huge bear-like creature interested solely in having them for breakfast.

David Innes and his captive, a member of the reptilian Mahar master race of the interior world of Pellucidar, return from the surface world in the Iron Mole invented by his friend and companion in adventure, Abner Perry. 

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.

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.

David Innes was a captive in Pellucidar, the strange world within a world that lies under the Earth’s crust. To rescue him, Tarzan comes into that savage, prehistoric land at the head of an expedition equipped with every modern device. But Pellucidar is not like the jungles the ape-man knows. Here are saber-toothed tigers and every savage creature from the beginning of time. Here the horizon curves back on itself and the sun hangs always in the middle of the sky. And now, for the first time, Tarzan is hopelessly lost in a land teeming with unknown, gigantic killers.