From New York Times bestselling author Lauren Oliver comes a novel about two very different girls connected by dark pasts. Lyra, known by the number 24, is a replica—human model—who was born, raised, and observed in a clandestine research facility called the Haven Institute. When Lyra escapes from Haven and meets Gemma, a stranger on a quest of her own, earth-shattering secrets are revealed. Replica is a flip book that contains two narratives in one, and it is the first in a duology. Each contains revelations critically important to the other story. The stories can be read separately or in alternating chapters. In either case, the two distinct parts of this astonishing novel combine to produce an unforgettable experience.