In the forbidding beauty of the mountains of Montenegro, with World War I a dark prophecy on the horizon, an English traveller, Auberon Harwell, happens upon a remote valley. He is posing as a botanist, but in reality is the confidential agent of a powerful English peer who recognises the seeds of advantage and threat in the region.
The Montenegrin Serbs are a fierce and independent people, whose greatest hero Danilo Pekocevic, warrior patriarch of the valley. His only son, Toma, loves a girl he cannot marry, the daughter of a neighbouring Muslim landowner. Harwell, against all reason and hope, falls in love with Toma's mother, who prays that her son may emigrate to escape this burden of violence and vengeance.
Harwell is bound by agonizing choices and the obligations of hounour, duty and love. Ultimately he is forced from his position of careful neutrality into a confrontation which shakes the foundations of the world he thought he knew...