From the #1 New York Times bestselling author of The Raven Boys, a mesmerizing story of dreams and desires, death and destiny. Something is happening to the source of the dreamers' power. It is blocked. Diminished. Weak. If it goes away entirely, what will happen to the dreamers and those who depend on them? Ronan Lynch isn't planning to wait and find out. Backed by his mentor, Bryde, he is ready to do what needs...