Initially published in English on 2 May 2019 by Hamish Hamilton in the UK and on 4 June 2019 by W. W. Norton & Company in the US, the book has been translated into over a dozen languages.

An audiobook, read by Matthew Waterson, was also released in June 2019 by HighBridge Audio.

The book is a descriptive journey by the author of different subterranean landscapes that he explores, including caving in the Mendip Hills, the Catacombs of Paris, the Karst Plateau, an underground laboratory for detecting evidence of dark matter, and descending into a glacier's moulin among other explorations.

Through these underground journeys the book sheds light on the impacts and consequences of human actions within the Anthropocene geological epoch.

It is a 2020 American Library Association Notable Book,[5] and has won The 2019 National Outdoor Book Award for Natural History Literature,[2] The 2019 Wainwright Prize for UK Nature Writing,[3] and was named the 2020 Stanford Dolman Travel Book of the Year at the Edward Stanford Travel Writing Awards.