At the Earth's Core is the 1914 fantasy-adventure by Edgar Rice Burroughs that launches his Pellucidar series. Wealthy David Innes and inventor Abner Perry test an experimental drilling machine that unexpectedly burrows 500 miles into the planet, emerging in the hidden inner world of Pellucidar. This Hollow Earth realm of eternal daylight teems with prehistoric beasts and is ruled by the telepathic, pterosaur-like Mahars who enslave primitive humans. Innes must navigate strange customs, fight for freedom, win Dian's love, and spark a revolt against the Mahars before trying to return to the surface world.