The Winternight Trilogy follows Vasya, a young woman living in the wilderness of medieval Russia, who possesses the ability to see the spirits of folklore that protect her home. As Christianity spreads and threatens the old ways, Vasya must navigate the conflict between the human world and the dangerous, fading realm of myth to protect her family and country from an ancient evil. Throughout the series, she grows from a rebellious girl into a powerful figure who must confront both historical upheaval and supernatural forces to save her people.