In Heir of Fire, Celaena Sardothien travels to Wendlyn on a mission but is emotionally broken after past traumas. There, she meets Rowan Whitethorn, a powerful Fae warrior who forces her to confront her pain and begin training to control her magical abilities. Through this journey, Celaena slowly discovers her true identity as Aelin Galathynius, the lost heir of Terrasen, and begins to accept her power and destiny.
Meanwhile, in Adarlan, Dorian struggles with dangerous hidden magic, while Chaol becomes involved in secret resistance efforts against the king. At the same time, the story introduces Manon Blackbeak, a ruthless witch-in-training whose storyline will become important later.