Taking place in the future, the government has issued a law that couples can only have two children. But families like Luke's, who is a third child, have decided not to follow the law. Because he is illegal, Luke has hidden all his life. Distant family members don't know he even exists. He has never been to school or met children other than his brothers.
All that changes when a new family moves in next door. Luke notices that when every one in that family leaves, there is a face in the window, and he wonders if they have a hidden child just like him.
I loved this book. It reminds me a little of The Gift by Lois Lowery. It was thrilling, and I never knew what was going to happen next. The way it grabs you and hooks you in by the end, you just have to read the others in the series to see what happens.