Martin lives in a perfect world. Every year, a new generation of children arrives on a conveyor belt to meet their parents. Every spring, the residents of this suburb take down the snow they've stuck to their windows and put up the flowers. Every morning, the residents gather around their televisions and vote for whatever matter of national importance the president has on the table. Today, it is the colour of his drapes. And on this particular day, which happens to be Martin's birthday, he receives his first pet - an Alldog, the smartest, most technologically advanced robotic pet in the world. But things are about to change. As Martin grows more and more curious about what makes his domed suburb run, he begins to wonder what lies outside the walls that have surrounded him his entire life. And when a man arrives to take a group of children away - a group which includes Martin's sister, Cassie - it's up to Martin to find a way out.