In 7th century Ireland, Artt, a highly regarded monk visits an unexceptional monastery, where he has a dream vision he believes is a message from God. He is to take two monks with him on a pilgrimage to found a new monastery on an untouched island far away from mankind. But the island isn't on the map, and the other two monks are honoured but feel they are unworthy. Trian is very young and lefthanded, and Cormac is old and marked by scars from his life before his vows. Nevertheless, the three men set sail into the unknown, searching for an island to claim in God's name. Alone in the sea except for the birds, it's up to their fellowship to find what God provides. And on a nearly vertical piece of rock so harsh that there's only one tree, and no animals that can't fly or swim away, their vows of poverty come to mean something more extreme. From these scant materials, they need to build an altar and a church, make quills and transcribe religious texts, all before giving thought to their earthly needs. But they have to survive to live in service of God, and they must always be humble and obedient. When those aims clash, the men must decide the true meaning of loyalty, piousness, and humanity.