Haven by Emma Donoghue

Three men vow to leave the world behind them. They set out in a small boat for an island their leader has seen in a dream, with only faith to guide them. What they find is the extraordinary island now known as Skellig Michael. Haven has Emma Donoghue's trademark world-building and psychological intensity--but this story is like nothing she has ever written before. 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 island inhabited by tens of thousands of birds, and claim it for God. In such a place, what will survival mean?