Spacer

K.C, a fifteen year old in Dystopian New York (known now as The Grounds), is a Spacer. Spacers are teenagers that are groomed to fit into a family, company, or otherwise in order to fill the space where someone once was. They aren't told why the person they're replacing is gone, and the family or company they're placed with has no recollection of the person being replaced, fully believing that the Spacer was always there.

K.C replaces a girl named Kathy Cass, a girl she had known before her days as a Spacer. A girl that had been her best friend. When Kathy's family starts hinting that they know K.C isn't their daughter, she must set out to figure out what really happened to Kathy, before the same thing happens to anyone else.