From a master of science fiction and one of the bestselling and most celebrated science fiction writers of his generation comes an electrifying new standalone novel of intrigue and existential reckoning.

What hides beneath the waves of an alien world?

On an island alone in the sea, a monastic community of clones live in the shadow of a wrecked spaceship. There are seven clone lineages in their Retreat, and just seven human faces in this world. They work, pray and replicate, knowing that all this was ordained - that their peaceful lives were intended by the Firstcomers who originally landed here. But the tide is about to turn.

While serving a punishment detail on the beach, rebellious clone Six-Maijo makes a harrowing discovery: a body has washed ashore with a face belonging to no known lineage. Despite the disapproval of his superiors, Maijo pursues the mystery until he learns some questions are best left un-asked. What happened to the other half of their wrecked ship? Why is the sea casting up its corpses - and why won't they stay dead?

As the community fractures under the pressure of ancient guilt, the sea gives up terrible secrets. The Retreat is under threat, but are its true enemies inside or outside its walls?