Two years after their adventures in The Land of the Silver Apples, the apprentice bard Jack and his Viking companion Thorgil confront the malevolent spirit of a vengeful mermaid and begin a quest that casts them among the fin folk of Notland.

Pen Ohmsford is charged with the task of rescuing his Aunt Grianne, held captive by a demon; but he is captured and taken to Parador by Druids who have been pursuing him, imprisoned, and deprived of the darkwand, his only means of crossing over into the Forbidding to rescue his aunt.

After escaping from the Sea of Trolls, the apprentice bard Jack plunges into a new series of adventures, traveling underground to Elfland and uncovering the truth about his little sister Lucy.