This collection of award-winning science fiction includes a story that was a finalist for the Hugo Awards and one that was voted one of the 10 greatest science fiction stories to appear during the 1990s. In the title piece, a geologist has downloaded the memories of his deceased mentor into a robot's electronic brain. Together, they bore through the crust and mantle to the very core of the planet Earth. Their work is complicated by a mysterious intelligence deep within the Earth and by the robot's own emergent humanity. The remaining stories comprise a variety of tales including a story about climbing in the Chilean Andes in which the protagonist is haunted by a ghost, and a tale about a battle-weary veteran who returns from a high-tech future to face his most sinister challenge at home.