In 1920s Ireland young doctor Damien O'Donovan prepares to depart for a new job in a London hospital. As he says his goodbyes at a friend's farm, British Black and Tans arrive, and a young man is killed. Damien joins his brother Teddy in the Irish Republican Army, but political events are soon set in motion that tear the brothers apart.

Margaret Hale is a southerner from a country vicarage newly settled in the industrial northern town of Milton. In the shock of her move, she misjudges charismatic cotton mill-owner John Thornton, whose strength of purpose and passion are a match for her own pride and willfulness. When the workers of Milton call a strike, Margaret takes their side, and the two are brought into deeper conflict. As events spiral out of control, Margaret - to her surprise - begins to fall in love with Thornton...

Set during the 1960s in the fictional North Yorkshire village of Aidensfield, this enduringly popular series interweaves crime and medical storylines.