In a world where survival is everything, what room is left for sacrifice?

Jimmy Hunter's days as a scavenger are over. Now he lives as a Keeper, one of the only survivors with knowledge of the humanity-saving underground bunkers. With the destruction of the Lifeboat in his city, Jimmy and his companions must find passage across the ocean to the next nearest Lifeboat in Scotland. Their only hope is to find the dwelling of Dr. Victoria Clarke and search for any clues she may have left to the secret bunker's location.

Unknown to them, this Lifeboat lies underneath an entire community of people living and thriving with no knowledge that the salvation of the world lies beneath their feet. Led by a charismatic man known as the Emissary, the community obeys his every whim, believing he is the messenger of God's judgment upon the world.

Jimmy, Elena, and Dr. Clay must face off with the cult leader, bringing a message of rescue that threatens to unravel the delicate thread of delusion holding the community together. Will the new Keepers locate the secret entrance to the Lifeboat? And what will the cost be to the community if they do?