In a dystopian future, after a shortage of food and overpopulation, families are limited to two children. Luke Garner, a 13-year-old boy, lives on a farm with his mother, father, and two brothers. As a third child, Luke and his parents are in violation of a law called the population law. Luke, like all third children, must spend his days hidden or away from public view, or else they will be killed or imprisoned, as well as their families. When the government starts building houses in the woods behind the Garners' house for rich, elite people who are Government officials, Luke is forced to hide in his house. During the day, when Luke's brothers are at school, and his parents are at work, Luke is home alone. One day, Luke sees the face of a child in a window of a house that he knows already has two children. About a month later, he secretly runs over to the house out of curiosity and is caught by Jen, the child who he saw in the window. She reveals that she is also a Shadow Child, a third child, just like Luke. Jen introduces Luke to a chatroom on her computer where he meets other Shadow Children like him. Jen and Luke become friends and Luke visits Jen as much as he can. Jen, who strongly disagrees with the Government, shows Luke books that explain what the Government is doing wrong. He takes these books home. Luke feels guilty for being born because the books tell him that Shadow Children use up resources that other people and animals are supposed to use. Luke then learns about the upcoming rally. Luke finally confesses that he doesn't want to go because he is too afraid. Jen, who feels betrayed, gets upset and tells him to leave as she doesn't need him anymore. He is annoyed and angry at Jen and wishes that the Population Police would shoot her during the rally. After thinking that, he realizes that he shouldn't have thought that. The next morning, Luke is paranoid about what has happened. There has been no report of any rally. Growing more afraid of what may have happened to Jen, after a few months, he breaks into her home again, but there is no sign of her. He runs into the computer room and logs into the chatroom. He sends a message in the chatroom asking where Jen is, but there is no reply. Overcome with his emotions, he reacts too slow as the door opens and a man steps into the room with a gun. He asks who Luke is and how he knows Jen's identity. Luke reveals himself as another Shadow Child who is friends with Jen. He demands to know where Jen is. The man, who is Jen's father, lowers the gun. He explains that Jen and all forty other children were shot and killed in the rally. Luke asks where were the other children because he was told that there would be a thousand. Mr. Talbot explains that she had too much faith in the other children. The Population Police suddenly turn up and demand to come in. The chatroom Luke had sent messages in had been secretly monitored after the rally. Luke hides while Mr. Talbot, who is revealed to be working for the Population Police as well, sorts things out. Mr. Talbot is on Luke's side and wants to avenge his daughter. Mr. Talbot forges a fake I.D. for Luke, so he can travel far away. Luke begins a new life as Lee Grant. He gets sent to a boarding school miles away from his farm and family, where he begins his new life.
