Lorcas Fellken is thirteen when his father gives him a rock for a birthday present. But not just any rock - this one is the cornerstone to an ancient castle. Years later, Lorcas moves to his family's summerhouse and begins reconstructing the castle, one stone at a time. Egged on by a shadow that lives under the stone, he adds layer after layer. But as he builds, the castle becomes more aware - and more malevolent. Lorcas slowly creates something he never imagined, despite the efforts of a mysterious group bent on keeping the castle from being rebuilt. Along the way, he gains surprising powers - for a price. Would the castle have been better left in ruins?