The story centres on an expedition led by Professor Lindenbrook down into the Earth's dark core. Members of the group include the professor's star student, Alec, and the widow of a colleague. Along the way lurk dangers such as kidnapping, death, sabotage by a rival explorer, and attacks by giant prehistoric reptiles. But they also encounter such magnificent wonders as a glistening cavern of quartz crystals, luminescent algae, a forest of giant mushrooms, and the lost city of Atalnatis.