Kelly Williams, dying of heart disease, receives a vampire's heart taken from another young woman. At sunset on the third day after the transplant, the heart awakens in Kelly's chest, healing her and invigorating her. On the other side of town, Wendy awakens to discover she's incomplete. Roberto, the vampire who changed her, should have been there by her side when she awoke to guide her into her new undead life. She's missing many of her most prized organs, and calls on an old admirer, Dwight, convincing him to help her. He soon learns she wants her heart back and realizes he's unable to refuse her.
Roberto, waiting for Wendy's intangible call on reawakening, receives a summons to the hospital where he instead finds Kelly. Their connection is immediate, but the reason for it is unclear. They part ways, only to meet again a night later, where their powerful reconnection puts them in immediate danger from agents of a cleverly disguised organization whose mission is to take vampires off the street before the public becomes aware of them.
Wendy's demand that her heart's return compels Dwight to interfere with Roberto and Kelly's quest for safety. Kelly struggles to survive physical threats and accept moral duty while trying to understand the forces arrayed for and against her. Is there true good and absolute evil, and why is the idea of Christ so disturbing to the undead?