The novel follows the experiences of a boy named Baz on his arrival at "X Isle" from the equally miserable "mainland".

Mainland survivors trade goods with people from Eck's Isle who occasionally take back boys with them.

But when they get to the island they discover conditions are harsh for the boys and that Preacher John, the head of the Eck family is a religious fanatic.

After some of the work boys die and Preacher John's sermons start emphasising sacrifices to God, they decide to build a bomb and destroy the boat then return to the mainland by dinghy.

Patrick Ness of the Guardian said that 'X Isle is a strong tale, well told, if perhaps lacking quite enough incident to fill 477 pages...