<p>On a promise to a friend, Miss Jane Marple came to Stoneygates to find out what was wrong. The college, a home for juvenile delinquents run by her friend's husband, also housed the step children of her previous marriages. But Miss Marple was soon surrounded by a world of illusion, not reality. In the words of the conjurer, "they do it with mirrors." But who? And why?</p>