"At the Earth's Core" is a science fiction novel written by Edgar Rice Burroughs, published in 1914. The story follows the adventures of David Innes, who travels to the center of the Earth using a drilling machine. There, he discovers a prehistoric world filled with strange creatures and ancient civilizations. In this underground realm, David Innes encounters various challenges, including battles with monstrous beings and interactions with the intelligent inhabitants known as the Mahars. The novel explores themes of exploration, survival, and the clash between different cultures in a fantastical setting beneath the Earth's surface.