From Lauren Oliver, New York Times bestselling author of Before I Fall and the Delirium trilogy, comes an epic, masterful novel that explores issues of individuality, identity, and humanity. Lyra's story begins in the Haven Institute, a clandestine research facility off the coast of Florida, where thousands of replicas, or human models, are born, raised, and observed. When a surprise attack is launched on Haven, two of its young experimental subjects? Lyra and the boy known only as 72?manage to escape. Gemma has been in and out of hospitals for as long as she can remember. After she is nearly abducted by a stranger claiming to know her, Gemma starts to investigate her family's past?and discovers her father's connection to the mysterious Haven research facility. Hungry for answers, she travels to Florida, only to stumble upon two replicas and a completely new set of questions. While the stories of Lyra and Gemma mirror each other, each contains breathtaking revelations critically important to the other story. Turn the book one way and read Lyra's story; turn the book over and upside down and read Gemma's story. The two distinct parts of this novel combine to produce an unforgettable experience for its two young heroines?and its reader.