From the bestselling author of I Know What You Did Last Summer, a thrilling doppelganger mystery that will keep you looking over your shoulder . . .Laurie Stratton finally has everything a sixteen-year-old could ever want. But just as her perfect summer comes to a close, things start to unravel when her boyfriend insists he saw her out with another guy—when Laurie was really home sick! More mysterious sightings convince Laurie someone very real is out there, watching her . . .The truth reveals a long-lost sister who has spent the years growing bitter and dangerous. She has learned how to haunt Laurie, but the visits soon become perilous. She wants something from Laurie—her life!Praise for Lois Duncan"She knows what you did last summer. And she knows how to find that secret evil in her characters' hearts, evil she turns into throat-clutching suspense in book after book. Does anyone write scarier books than Lois Duncan? I don't think so." —R. L. Stine, #1 New York Times–bestselling author"There are a lot of smart authors, and a lot of authors who write reasonably well. Lois Duncan is smart, writes darn good books and is one of the most entertaining authors in America." —Walter Dean Myers, New York Times–bestselling and Printz Award-winning author"I couldn't be more pleased that Lois Duncan's books will now reach a new generation of readers." —Judy Blume, #1 New York Times–bestselling author