In this beautiful story of adventure and survival from the New York Times bestselling author of Room, three men vow to leave the world behind them as they set out in a small boat for an island their leader has seen in a dream, with only faith to guide them.

In seventh-century Ireland, a scholar and priest called Artt has a dream telling him to leave the sinful world behind. Taking two monks--young Trian and old Cormac--he rows down the river Shannon in search of an isolated spot on which to found a monastery. Drifting out into the Atlantic, the three men find an impossibly steep, bare rock inhabited by tens of thousands of birds, and claim it for God. In such a place, what will survival mean?