David Sempill, a parish minister in the seventeenth-century Scottish Borders, confronts a sinister resurgence of ancient witchcraft within the Wood of Caledon while navigating the volatile political landscape of the Wars of the Covenant. Sempill attempts to protect his congregation from both the encroaching influence of devilry and the pervasive hypocrisy of his peers. His objective is complicated by his divided loyalties between his religious duties and his political sympathies for the Marquis of Montrose. The narrative operates within a framework of historical realism, utilizing the tension between rational faith and the primal, subliminal forces of the natural world. The prose reflects the author's classical education, grounding the supernatural elements in a structured, atmospheric environment.

Readers and critics frequently highlight the novel's ability to blend historical accuracy with a haunting, supernatural atmosphere. Discussion often centers on the protagonist's internal struggle as he attempts to reconcile his spiritual calling with the harsh realities of civil war. Many observers note the author's sophisticated use of classical symbolism to represent the darker aspects of the human psyche. The pacing is often described as deliberate, allowing the tension to build alongside the political and religious instability of the era. Readers appreciate the depth of the setting, which serves as both a physical location and a metaphor for the challenges to reason.