The story is set in the Scottish Highlands and revolves around the traditional belief in "the Second Sight," a supposed supernatural ability to perceive future events or hidden spiritual truths. MacDonald uses this idea not just as folklore, but as a way to explore deeper questions about perception, destiny, and spiritual awareness. At the center of the narrative is a haunting "portent" (an omen or vision) that reveals a tragic fate tied to a Highland family. The characters are caught between ordinary reality and unsettling visions that seem to predict or reflect moral and spiritual consequences beyond human control.