Paul follows the River Ayr as it flows from Loch Glenbuck towards the sea and the Clyde coast. The old mining village of Glenbuck was demolished long ago, but its memory is kept alive by former resident Barbara Alexander whose uncle, the famous Liverpool football manager Bill Shankly, was a Glenbuck man. From Glenbuck, Paul follows the river through a landscape pockmarked by the scars of old mineral extraction and industry.
At Muirkirk he discovers how a local man illuminated the cities of the world with gas lighting, and how a certain Mr McAdam invented tarmac for the roads of the world. The course of the river Ayr flows through land rich in covenanting history when religious conflict cost many lives. In the Ayr gorge, Paul encounters the extraordinary tale of the radical preacher Alexander Peden, whose life on the run forced him to hide in caves while still preaching hellfire sermons to the people.
Finally reaching the coast, Paul visits the only working salt evaporation tower in the world. Here, with a pinch of salt, he learns how sea water is evaporated by wind and sun to make brine, from which sea salt is made.