by Philip Reeve
In this dystopian world, cities compete with each other in a kind of social Darwinism. Cities are on wheels and the larger ones are gobbling up the smaller towns. London is one of the big bullies and is on the hunt. There have been rumors that there is still some green space out there in the world, but it is up to an outcast historian and a girl with a scarred face to save this world before London succeeds in its atrocious plan.