Reunited with Zavilia, Fia and her companions enjoy a peaceful and relaxing time on Blackpeak Mountain, getting to know the dragons and picking herbs. But their fun is cut short when they encounter a young woman with black hair and eyes—traits of a demon! As they face a dangerous foe unseen by mankind in over three hundred years, Fia finds herself questioning everything they thought they knew about demons. And if what they know about demons is wrong, how many more of them could be out there walking among them?