In "Among the Hidden" by Margaret Peterson Haddix, the story follows Luke, a third child who lives in hiding due to strict population control laws that forbid families from having more than two children. Luke discovers another shadow child named Jen, who is determined to challenge these oppressive laws, and he faces a choice between the safety of remaining hidden and the risk of joining her rebellion. The narrative explores themes of freedom, identity, and the consequences of governmental control over individual lives.