The world has been decimated by a mysterious plague. There is no permanent cure. Only those resistant to it, called "Sisters", can treat it by absorbing the toxins created by the disease. They may save the person, but this shortens their lifespan drastically -- once they absorb a certain amount, they die. A fun series that was tragically Cut Short after laying down the foundations of its main arc plot. What made its cancellation so heartbreaking was the amount of foreshadowing set up and Left Hanging.