In the futuristic world where Baz lives, climate change and terrible storms have flooded his continent -- and from what he know -- the entire world. There's hardly any land left that's suitable for living on -- in most areas all you can see are rooftops and towers sticking out of the water. With the waters completely polluted and nowhere to grow food, everyone is scavenging for supplies to keep themselves alive. There is one place though, that is still above the waters and supposedly has plenty of food: X-Isle. It is controlled by Preacher John and his sons who operate a salvaging business, diving for whatever items have survived the waters and trading with people on the mainland. They come regularly to the mainland to recruit young boys to work for them, taking the ones who offer the best items as payment.
 
Baz can hardly believe it when he is chosen. He doesn't quite know what to expect, but rumours suggest that it's a much better place and he'll at least get three meals a day. However, when he and another boy, Ray, arrive at the island, they discover things aren't as everyone on the mainland had believed. Preacher John's sons run the island like tyrants and everyone is bullied by two older, favoured boys, Steiner and Hutchinson. They have to fight each other for one can of food a day, carry heavy loads of rocks until their hands bleed and clean dangerous, disgusting filth off savaged items. Preacher John is an enormous, intimidating man who only appears on Sundays to preach a cryptic and terrifying sermon that everyone is forced to attend. There are far fewer boys on the island than Baz expected -- they'd been taking many more recruits to the island and Baz doesn't remember seeing them return to the mainland. He wonders if something sinister is going on and realizes that time might be running out for him and the other boys when Preacher John begins to talk about making sacrifices to God so that the waters will recede.

The plot kept me intrigued for pretty much the entire book. Preacher John is presented as a maniacal dictator with warped religious ideas. This gave him an unpredictability and potential for evil that kept the suspense up. (I really did think that he might do something really terrible...)

A lot of the book focused on the dynamics between the boys and their struggle to survive the abuse from Steiner, Hutchinson and Preacher John's sons rather than efforts to deal with the world disaster. I found that the dystopian setting wasn't crucial -- the story could have taken place in our present world, in any dire situation that might make a person willing to leave family and endure even more trouble.

There were a couple predictable plot points in the book that I thought could have been more subtle, but in general I enjoyed this one quite a bit. Characters and their emotions were believable, and only a slight suggestion of romance at the end. It's one I'd definitely recommend.