Discover the twisty, gripping story from the acclaimed author Clare Mackintosh. 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.

She takes it home to her family, who are convinced it's just someone who looks like Zoe. 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...

With the help of a determined cop, Zoe uncovers the ad's twisted purpose—a discovery that turns her paranoia into full-blown panic. For now, Zoe is sure that someone close to her has set her up as the next target. And now that man on the train—the one smiling at Zoe from across the car—could be more than just a friendly stranger. He could be someone who has deliberately chosen her and is ready to make his next move.