Christa Parravani and her identical twin, Cara, were linked by a bond that went beyond sisterhood or friendship. But haunted by childhood experiences with father figures and further damaged by being raped as a young adult, Cara descended into depression, drugs and a shocking early death. A few years later, Christa read that when an identical twin dies, 50 percent of the time the surviving twin dies within two years. First, Christa fought to stop her sister's downward spiral; suddenly, she was struggling to keep herself alive.