"At the Earth's Core" by Edgar Rice Burroughs is a fantasy novel published in 1914. When an experimental drilling machine cannot be stopped, inventor David Innes and his companion burrow five hundred miles beneath Earth's surface, emerging into Pellucidar—a hollow world within our planet. There they encounter prehistoric creatures and intelligent pterosaur-like beings called Mahars who enslave the primitive human inhabitants. Innes must navigate dangerous misunderstandings, win the heart of a captive woman, and lead a desperate rebellion against their reptilian overlords. (This is an automatically generated summary.)