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 – 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 leave them utterly helpless, alone in their terror and confusion. Except they're not all as helpless as he thinks ...