When Zoe Walker sees her photo in the classifieds section of a London newspaper, she is determined to find out why it's there. There's no explanation: just a grainy image, a website address and a phone number. Fist she is convinced it's just someone who looks like her. But the next day the advert shows a photo of a different woman, and another the day after that. Is it a mistake? A coincidence? Or is someone keeping track of every move they make? An edge-of-your-seat, page-turning psychological thriller.