Only We Know — Simon Packham

Lauren's family have moved house very suddenly, and she and her sister Tilda have to go to a new school. Lauren's determined to reinvent herself, but she's panic-stricken when she sees Harry, who she knew a few years ago. Luckily Harry doesn't recognize her, and she knows she has to make sure it stays like that. Lauren, unlike Tilda, settles in well. She makes friends, is helping to organize the school fashion show, and has boys asking her out. But just as her life finally seems to be looking up she starts receiving macabre packages. When she gets a message: "Isn't it time your new friends knew all about you?" she has to admit that someone knows her secret. But who -- and what should she do?