Dr. Susan Ryerson, a young genetic researcher, stumbles across an unconscious woman with mortal injuries. But impossibly, the woman returns to life, and Dr. Ryerson discovers that she has crossed paths with something that is more than human. Ryan Alexander, her enigmatic patient, possesses extraordinary capabilities, an inconceivable anatomy, and a devastating charisma. She draws Susan into a violent and erotic world that places both the doctor and her young son in danger. Ryan, through her vivid dreams and through the memories of the others, relives her six centuries of life, all the while knowing that history is accelerating to catch up with her.