NATIONAL BESTSELLER • "Part horror tale, part mystery, part romance ... utterly fantastic.”—O, The Oprah Magazine • The bestselling, award-winning author of A Visit from the Goon Squad brilliantly conjures a world from which escape is impossible and where the keep—the tower, the last stand—is both everything worth protecting and the very thing that must be surrendered in order to survive. Two cousins, irreversibly damaged by a childhood prank, reunite twenty years later to renovate a medieval castle in Eastern Europe. In an environment of extreme paranoia, cut off from the outside world, the men reenact the signal event of their youth, with even more catastrophic results. And as the full horror of their predicament unfolds, a prisoner, in jail for an unnamed crime, recounts an unforgettable story that seamlessly brings the crimes of the past and present into piercing relation.