If you have a sister and she dies, do you stop saying you have one? Or are you always a sister, even when the other half of the equation is gone? At thirteen, most people don't know their life's purpose. But Anna has had a purpose since the day she was conceived: to keep her sister alive. Anna was created to be a perfectly matched donor for her sister, Kate, to help fight Kate's leukemia. For Anna, it's meant thirteen years of hospital visits and painful medical procedures. But you'd do anything to save your sister's life - right? That's what her family thinks. So when Kate needs a new kidney and Anna makes an unthinkable decision, it sends everyone reeling. A heartbreaking story of courage and self-sacrifice, which redefines right and wrong. How do you find the answer to an impossible question? And when it comes to life, death and love, is enough ever enough?
