From the #1 New York Times bestselling author of The Passage comes a riveting standalone novel about a group of survivors on a hidden island utopia--where the truth isn't what it seems.Founded by a mysterious genius, the archipelago of Prospera lies hidden from the horrors of a deteriorating outside world. In this island paradise, Prospera's lucky citizens enjoy long, fulfilling lives until the monitors embedded in their forearms, meant to measure their physical health and ps