Julian and Elias Thorne were born as a perfect symmetry—two identical halves of a single, haunting blueprint. But as children locked in a coal cellar, they learned a terrifying survival tactic: The Swap. To endure their father's rage, they practiced becoming one another, a psychological game that blurred the lines of their identities until the "good" twin and the "spare" twin became indistinguishable.Thirty years later, the game has turned into a masterpiece of carnage.