Nancy Drew: Secrets Can Kill Cheats

On almost every bulletin board in the school are pieces
of paper stuck with pushpins that have messages that do not make
any sense. Take a real mirror and hold it up to the paper displayed
on screen. Also, in the library there are some books and charts
with secret codes. One is "Don't run Nancy" and another
is "The bolt cutter you must take!".
Strategy: by Linda Shaw