The missing don't always want to be found. Kate Harlow recognizes this painful truth, even as she keeps searching for her daughter, Sophie, who disappeared two years ago. The police have stopped investigating--after all, Sophie has sent postcards home, insisting that she's fine. To fill the space in her increasingly empty days, Kate volunteers at Message in a Bottle, where runaways can leave messages for loved ones, no questions asked. Then one evening, a call comes in from a voice Kate instinctively recognizes, even through bursts of static and beyond the sudden dial tone that breaks their connection. Those closest to Kate worry she's cracking under her grief, imagining that it was Sophie. But Kate knows--that it her daughter on the phone. And that a stranger has been inside her house. Watching her. Sophie is out there. And Kate has to find her, even if someone will try anything to stop her . . .