Perfect Ruin - Lauren DeStefano

From the New York Times bestselling author of The Chemical Garden trilogy: On the floating city of Internment, you can be anything you dream. Unless you approach the edge. Children's Literature says "shades of Aldous Huxley's Brave New World and George Orwell's 1984 inspire DeStefano's sci-fi/murder mystery page-turner."
Morgan Stockhour knows getting too close to the edge of Internment, the floating city and her home, can lead to madness. Even though her older brother, Lex, was a Jumper, Morgan vows never to end up like him. There's too much for her on Internment: her parents, best friend Pen, and her betrothed, Basil. Her life is ordinary and safe, even if she sometimes does wonder about the ground and why it's forbidden.
Then a murder, the first in a generation, rocks the city. With whispers swirling and fear on the wind, Morgan can no longer stop herself from investigating, especially once she meets Judas. Betrothed to the victim, Judas is being blamed for the murder, but Morgan is convinced of his innocence. Secrets lay at the heart of Internment, but nothing can prepare Morgan for what she will find--or whom she will lose.