This book is about Cinder, a cyborg, who is living in New Beijing after World War IV. She has a stepmother and two stepsisters (much like Cinderella) who are getting prepared for a ball for Prince Kai. One day, when she is at her shop in the market square, Kai approaches her and wants her to fix his robot. She agrees to it, and meanwhile, her stepsister Peony comes down with letumosis, something similar to the Black Plague and has no known cure. With Peony sick, Cinder's stepmother Adri enlists Cinder to be tested for a cure for letumosis, knowing full well that all those tested never live to tell about it. While in the lab, it is discovered that Cinder is immune. She finds out that she is really Lunar, from a colony on the moon, but it is illegal for Lunar to live on earth. Knowing that this must be kept a secret, and despite Kai's persistent courting of her, she decides to run away, but then finds out imperitive information that Kai must know. Will she be able to get to Kai in time or will she go through with her plan to run away to Europe?