An experienced investigator and his mystic companion travel to a mountain cave blamed for a series of gruesome deaths and set about uncovering the cause. Their inquiries expose a mixture of occult menace, cryptic warnings, and unsettling confidences that draw in a woman who becomes implicated, a London acquaintance, and a religious figure, while a larger group weighs a crucial decision. The plot interweaves detection, spiritual confrontation, and personal reckonings, examining tensions between sceptical enquiry and mysticism, the exertion of occult influence, struggles of conscience, and the pursuit of fate and emotional resolution.