Wife. Mother. Spy. A double life is no life at all. Since the disappearance of her husband in 1951, Laura Leverett has been living in limbo with her daughter in Geneva. All others see is her conventional, charming exterior; nobody guesses the secret she is carrying. Her double life began years ago, when she stepped on to the boat which carried her across the Atlantic in 1939. Eager to learn, and eager to love, she found herself suddenly inspired by a young Communist woman she met on the boat. In London she begins to move between two different worlds - from the urbane society of her cousins and their upper class friends, to the anger of those who want to forge a new society. One night at a party she meets a man who seems to her to combine both worlds, but who is hiding a secret bigger than she could ever imagine. Impelled by desire, she finds herself caught up in his hidden life. Love grows, but so do fear and danger

Ruby's blood holds the secret to the Water that keeps her and her fellow Congregants alive and enriches Darwin West, who has enslaved them for two centuries, but when her romance with an Overseer, Ford, brings her freedom in the modern world, she faces a terrible choice.