A Court of Frost and Starlight - BY Sarah J. Maas

Feyre, Rhysand, and their friends are still busy rebuilding the Night Court and the vastly altered world beyond, recovering from the war that changed everything. But Winter Solstice is finally approaching, and with it, the joy of a hard-earned reprieve.
Yet even the festive atmosphere can't keep the shadows of the past from looming. As Feyre navigates her first Winter Solstice as High Lady, her concern for those dearest to her deepens. They have more wounds than she anticipated-scars that will have a far-reaching impact on the future of their court.
Bridging the events of A Court of Wings and Ruin with the later books in the series, A Court of Frost and Starlight explores the far-reaching effects of a devastating war and the fierce love between friends