Nightmare by Joan Lowery Nixon (Very good, 2003, PBk, 166 pgs, Yearling)

Used in very good condition. Cover has a crease. ISBN 9780440237730

   Emily has never fit in with her overachieving family. Instead of getting straight As, she sits in the back row and hides behind her hair. As a result, her parents have enrolled her for the summer at Camp Excel, an academic camp for underachievers. Emily doesn’t want to go, and not just because she thinks it isn’t necessary. Since she was a child, she’s been plagued by a recurring nightmare. And something about this camp feels familiar. Has she been there before? Why can’t she remember?
        With the help of two new friends, Emily discovers that her nightmare is not just in her head. Someone at Camp Excel has a secret and will do anything—even kill—to keep Emily from uncovering the truth.