Luke Garner, an illegal third child living with a fake ID, is going by the alias Lee Grant at the Hendricks School for Boys. He is at first confused and paranoid, as well as treated brutally by his roommates. Eventually, Luke begins sneaking out of the school to do things, and tries to plant his own garden in the woods. He soon begins spying on the same group of people abusing him in his room once he realizes that they trampled his garden.
He reveals himself to them, finding out that they are other illegals as well. The leader, Jason Barstow, otherwise known as Scott Renault, is outwardly a huge admirer of Jen Talbot, a friend of Luke's who died at a rally for third children's rights. However, the later part of the book reveals that he is a Population Police operative and is trying to get the group's real names only to betray them. Luke is accepted into Jason's group, but is still too frightened to give his real name.
He learns more and more about Hendricks School, but never learns what his schedule is until he is asked about "finals" by Jason. He then is told that he has to take his semester final tests, and that his results will be sent to his fake parents, the Grants. While staying up late to study, Luke happens to overhear a phone conversation of Jason's, where he is talking to a Population Police officer.
Luke finally realizes who Jason really is and attacks him with a history book causing the phone to get disconnected. He comes up with a cover story for the Population Police officer at the other end and gets Jason down to the nurse's office. He calls Mr. Talbot, a double agent at the Population Police and convinces him to come to Hendricks School. When other officers come, Mr. Talbot convinces them that Jason is lying about the third children and has Jason arrested along with Nina, his accomplice at the nearby Harlow's School for Girls. Luke is later given the choice to leave the school but decides to stay there and help the other third children and start an agriculure class.
