Zoe, Jennifer, and Nadia are three women with nothing in common. Except for the man who wants to kill them. He sends them terrifying letters, full of the intimate details of their lives — the clothes they wear, their little habits, how they act when they think they're alone — and promises that he will bring those lives to a violent, horrible end. But not before he has enjoyed himself. Invisible and apparently unstoppable, he delights in watching the women suffer, thrilled by his power to destroy their lives and their faith in those closest to them; to leave them utterly helpless, alone in their terror and confusion. But they're not all as helpless as he thinks ...