For as long as Molly Southbourne can remember, she's been watching herself die. Whenever she bleeds, another Molly is born, identical to her in every way and intent on her destruction. Molly knows every way to kill herself, but she also knows that as long as she survives she'll be hunted. No matter how well she follows the rules, eventually the Mollys will find her. Can Molly find a way to stop the tide of blood, or will she meet her end at the hand of a girl who looks just like her?