One hundred years after the fall of Hybern, the Court of Dreams has lived in peace: Feyre and Rhys have a daughter; Cassian and Nesta still circle each other; and Elaine and Lucien have found a tentative peace. But as Pyrthians - both fae and human - prepare to celebrate 100 years of peace, a mysterious stranger with an odd power arrives, and no one is sure if peace will last.