Chris Guthrie and her son, Ewan, have come to the industrial town of Duncairn, where life is as hard as the granite of the buildings all around them. These are the Depression years of the 1930s, and Chris is far from the fields of her youth in Sunset Song. In a society of factory owners, shopkeepers, policemen, petty clerks and industrial labourers, 'Chris Caledonia' must make her living as bets she can by working in Ma Cleghorn's boardinghouse.

Ewan finds employment in a steel foundry and tries to lead a peaceful strike against the manufacture of armaments. In the face of violence and police brutality, his socialist idealism is forged into something harder and fiercer as he becomes a communist activist ready to sacrifice himself, his girlfriend and even the truth itself, for the cause.

Grey Granite is the last and grimmest volume of the Scots Quairtrilogy. Chris Guthrie is one of the great characters in Scottish Literature and no reader of Sunset Song and Cloud Howe should miss this last rich chapter in her tale.