Tess loves math. She likes the way it is predictable and leads to single, correct answers. She maps her friendships with Venn diagrams and she thinks through problems with her peers by considering what makes someone's power over another person less than, greater than, or equal to.
When her mom discloses some suspicions about the death of her coworker's wife, Tess is sure that the single, correct answer to this situation is to inform the police. Her mother and father disagree with this solution and Tess has promised not to talk to anyone about it. She is trapped in a problem with an answer that is "D.N.E."--"does not exist".
The characters in this novel were thoughtfully developed and even though Tess has a particular, mathematical way of viewing the world, she still has many universal middle-schoolish struggles. She's trying to define her own morals and she relies on her best friends to help her figure things out.
The resolution was a surprise and the situations that push Tess to make difficult choices keep the plot moving right along. Even though some of the math references are beyond sixth grade, I think many of my students will enjoy this book.