Macfarlane descends — into caves beneath Somerset, into the Paris catacombs, into a salt mine in Slovenia, into the bedrock of Finland where nuclear waste will be buried for 100,000 years. A book about what lies beneath: time, death, and the dark matter of the planet.
Macfarlane follows ancient paths on foot — the Icknield Way, pilgrimage routes in the Himalayas, sea-roads in the Outer Hebrides, paths through Palestine. A meditation on what walking old routes does to the mind and body, and what landscapes remember.