The final book in the acclaimed Southern Reach Trilogy, following ANNIHILATION and AUTHORITY. It is winter in Area X. A new team embarks across the border, on a mission to find a member of a previous expedition who may have been left behind. As they press deeper into the unknown - navigating new terrain and new challenges - the threat to the outside world becomes only more daunting. The mysteries of Area X may have been solved, but their consequences and implications are no less profound - or terrifying.