The story opens in the wild landscape of Shetland at the end of the seventeenth century, where a reclusive stranger named Basil Mertoun lives in isolation at Jarlshof with his son Mordaunt. While the local inhabitants struggle against harsh elements and economic hardships under absentee landlords, Mordaunt thrives in this rugged environment, becoming skilled in local survival and deeply attached to the region's folklore. He frequently visits the hospitable Magnus Troil, a wealthy local magnate of ancient Norwegian descent, and forms a complex bond with the Udaller's two distinct daughters, the pensive Minna and the cheerful Brenda. Tensions rise when a shipwreck off the stormy coast introduces a charismatic and mysterious captain named Clement Cleveland to the community.
Cleveland quickly integrates into the social life at Burgh-Westra, capturing the attention of the local women and overshadowing Mordaunt's standing among his lifelong friends. As Mordaunt navigates this sudden alienation, he encounters the enigmatic and powerful local figure Norna of the Fitful-head, whose supposed mastery over the elements and dark past cast a long shadow over the islands. The narrative develops through a series of shifting loyalties, regional disputes led by an incoming Scottish factor attempting agricultural reforms, and the lingering mystery of Cleveland's true background and motives. The tension culminates during a grand summer festival where long-standing relationships are tested, old secrets begin to surface, and the fragile peace of the remote archipelago is threatened by both human passions and the unpredictable forces of the northern sea.
