The Sky Inside (The Sky Inside #1)

Martin lives in a seemingly perfect, genetically-engineered world under the protective dome of suburb HM1. But when a stranger arrives to take away all the young children, including his sister Cassie, and no one will explain where they've gone, Martin faces a difficult choice. He can stay in the dubious safety of HM1, where danger lurks beneath the surface, or venture into the mysterious, rumored-to-be-barren land outside the suburb to find answers.