The Teacher by Freida McFadden

Eve has a good life. She gets up each day, gets a kiss from her husband Nate, and heads off to teach math at the local high school. All is as it should be. Except. Last year, Caseham High was rocked by a scandal, with one student, Addie, at its center. And this year, Eve is dismayed to find the girl in her class. Addie can’t be trusted. She lies. She hurts people. She destroys lives. At least, that’s what everyone says. But nobody knows the real Addie. Nobody knows the secrets that could destroy her. And Addie will do anything to keep it quiet.