Luke Garner is an illegal third child. All his life has been spent in hiding. Now, for the first time, Luke is living among others. He has assumed a deceased boy's identity and is attending Hendricks School for Boys, a windowless building with cruel classmates and oblivious teachers. Luke knows he has to blend in, but he lives in constant fear that his behavior will betray him.

Then one day Luke discovers a door to the outside. He knows that beyond the walls of Hendricks lie the secrets he is desperate to uncover. What he doesn't know is whom he can trust -- and where the answers to his questions may lead him...

Luke has never been to school. He's never had a birthday party, or gone to a friend's house for an overnight. In fact, Luke has never had a friend.

Luke is one of the shadow children, a third child forbidden by the Population Police. He's lived his entire life in hiding, and now, with a new housing development replacing the woods next to his family's farm, he is no longer even allowed to go outside.

Then, one day Luke sees a girl's face in the window of a house where he knows two other children already live. Finally, he's met a shadow child like himself. Jen is willing to risk everything to come out of the shadows—does Luke dare to become involved in her dangerous plan? Can he afford not to?