The Raven King by Maggie Stiefvater

As their quest to find a sleeping Welsh king reaches its end, a malevolent force awakened on the ley lines threatens to unmake everything they’ve fought for in Henrietta. Blue, Gansey, Ronan, Adam, and their allies must navigate tangled magic, uncover truths about dreaming and lineage, and face the cost of a long-foretold death. Friendships and romances deepen under pressure as loyalties are tested and sacrifices demanded. In a bittersweet, fiercely hopeful finale, they confront the darkness and the prophecy that has defined them, reshaping their futures in the process.

Purchase from Bookshop.org